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 = 7336 
WHERE 
  cscart_products_categories.product_id IN (
    94761, 94763, 94765, 94816, 94950, 94951, 
    94956, 94957, 95566, 95569, 95571, 
    95574, 95575, 95578, 95579, 95580, 
    95581, 95587, 95588, 95589, 95590, 
    95591, 95629, 95630, 95631, 95632, 
    95633, 95634, 95635, 95636, 95637, 
    95641, 95642, 95643, 95644, 95647, 
    95648, 95649, 95650, 95651, 95652, 
    95655, 95656, 95657, 95658, 95659, 
    95660, 95935, 95938, 95939, 95942, 
    95943, 96213, 96214, 96215, 96216, 
    96217, 96218, 96219, 96220, 96221, 
    96222, 96223, 96224, 96225, 96226, 
    96227, 96228, 96229, 96230, 96231, 
    96232, 96233, 96234, 96235, 96236, 
    96237, 96238, 96239, 96240, 96241, 
    96242, 96243, 96244, 96334, 96336, 
    96338, 96340, 96341, 96342, 96343, 
    96344, 96345, 96346, 96347, 96348
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00272

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "138.82"
    },
    "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": 244,
            "rows_produced_per_join": 244,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "24.75",
              "eval_cost": "24.40",
              "prefix_cost": "49.15",
              "data_read_per_join": "3K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`nuie_scalesta_net`.`cscart_products_categories`.`product_id` in (94761,94763,94765,94816,94950,94951,94956,94957,95566,95569,95571,95574,95575,95578,95579,95580,95581,95587,95588,95589,95590,95591,95629,95630,95631,95632,95633,95634,95635,95636,95637,95641,95642,95643,95644,95647,95648,95649,95650,95651,95652,95655,95656,95657,95658,95659,95660,95935,95938,95939,95942,95943,96213,96214,96215,96216,96217,96218,96219,96220,96221,96222,96223,96224,96225,96226,96227,96228,96229,96230,96231,96232,96233,96234,96235,96236,96237,96238,96239,96240,96241,96242,96243,96244,96334,96336,96338,96340,96341,96342,96343,96344,96345,96346,96347,96348))"
          }
        },
        {
          "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": 12,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "61.00",
              "eval_cost": "1.22",
              "prefix_cost": "134.55",
              "data_read_per_join": "31K"
            },
            "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": 12,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "3.05",
              "eval_cost": "1.22",
              "prefix_cost": "138.82",
              "data_read_per_join": "195"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}