SELECT 
  cscart_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      cscart_products_categories.link_type = "M", 
      CONCAT(
        cscart_products_categories.category_id, 
        "M"
      ), 
      cscart_products_categories.category_id
    )
  ) AS category_ids, 
  product_position_source.position AS position 
FROM 
  cscart_products_categories 
  INNER JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
  AND cscart_categories.storefront_id IN (0, 1) 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  LEFT JOIN cscart_products_categories AS product_position_source ON cscart_products_categories.product_id = product_position_source.product_id 
  AND product_position_source.category_id = 7168 
WHERE 
  cscart_products_categories.product_id IN (
    100302, 100303, 100304, 100305, 100306, 
    100307, 100308, 100309, 100310, 100311, 
    100312, 100313, 100314, 100315, 100316, 
    100317, 100318, 100319, 100320, 100327, 
    100328, 100329, 100330, 100331, 100332, 
    100333, 100334, 100335, 100336, 100337, 
    100338, 100339, 100340, 100341, 100342, 
    100343, 100344, 100345, 100346, 100347, 
    100348, 100349, 100350, 100351, 100352, 
    100353, 100354, 100355, 100356, 100357, 
    100359, 100360, 100438, 100439, 100440, 
    100441, 100442, 100443, 100444, 100445, 
    100446, 100447, 100448, 100449, 100450, 
    100451, 100452, 100453, 100454, 100455, 
    100456, 100457, 100458, 100459, 100460, 
    100461, 100462, 100463, 100464, 100465, 
    100466, 100467, 100468, 100469, 100470, 
    100471, 100472, 100473, 100474, 100475, 
    100476, 100928, 100929, 100944, 100945, 
    100948
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00096

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "54.77"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY",
              "link_type",
              "pt"
            ],
            "key": "pt",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 96,
            "rows_produced_per_join": 96,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "9.89",
              "eval_cost": "9.60",
              "prefix_cost": "19.49",
              "data_read_per_join": "1K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`nuie_scalesta_net`.`cscart_products_categories`.`product_id` in (100302,100303,100304,100305,100306,100307,100308,100309,100310,100311,100312,100313,100314,100315,100316,100317,100318,100319,100320,100327,100328,100329,100330,100331,100332,100333,100334,100335,100336,100337,100338,100339,100340,100341,100342,100343,100344,100345,100346,100347,100348,100349,100350,100351,100352,100353,100354,100355,100356,100357,100359,100360,100438,100439,100440,100441,100442,100443,100444,100445,100446,100447,100448,100449,100450,100451,100452,100453,100454,100455,100456,100457,100458,100459,100460,100461,100462,100463,100464,100465,100466,100467,100468,100469,100470,100471,100472,100473,100474,100475,100476,100928,100929,100944,100945,100948))"
          }
        },
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "nuie_scalesta_net.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 4,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "24.00",
              "eval_cost": "0.48",
              "prefix_cost": "53.09",
              "data_read_per_join": "12K"
            },
            "used_columns": [
              "category_id",
              "usergroup_ids",
              "status",
              "storefront_id"
            ],
            "attached_condition": "((`nuie_scalesta_net`.`cscart_categories`.`storefront_id` in (0,1)) and ((`nuie_scalesta_net`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`nuie_scalesta_net`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`nuie_scalesta_net`.`cscart_categories`.`usergroup_ids`))) and (`nuie_scalesta_net`.`cscart_categories`.`status` in ('A','H')))"
          }
        },
        {
          "table": {
            "table_name": "product_position_source",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id",
              "product_id"
            ],
            "key_length": "6",
            "ref": [
              "const",
              "nuie_scalesta_net.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 4,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "1.20",
              "eval_cost": "0.48",
              "prefix_cost": "54.77",
              "data_read_per_join": "76"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}