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 = 7171 
WHERE 
  cscart_products_categories.product_id IN (
    84829, 84840, 84841, 91113, 91199, 91254, 
    83550, 83551, 83552, 83553, 86617, 
    86686, 83039, 90875, 90954, 85056, 
    85142, 85188, 85234, 84816, 84817, 
    86493, 86495, 86769, 86771, 91144, 
    85307, 85309, 85404, 85406, 85455, 
    85457, 85506, 85508, 82624, 83489, 
    85096, 83555, 83556, 86490, 86766, 
    85304, 85401, 85452, 85503, 86618, 
    86687, 85353, 85355, 83040, 90876, 
    90955, 83350, 83351, 83352, 83353, 
    85054, 85055, 85140, 85141, 85186, 
    85187, 85232, 85233, 82812, 82814, 
    82885, 82887, 82958, 82960, 83332, 
    83334, 83342, 83344, 85350, 83026, 
    83027, 90862, 90863, 90941, 90942, 
    82809, 82882, 82955, 83329, 83339, 
    85094, 85095, 83549, 83554, 86491, 
    86767, 85305, 85402, 85453, 85504
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00267

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "109.29"
    },
    "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": 192,
            "rows_produced_per_join": 192,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "19.53",
              "eval_cost": "19.20",
              "prefix_cost": "38.73",
              "data_read_per_join": "3K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`nuie_scalesta_net`.`cscart_products_categories`.`product_id` in (84829,84840,84841,91113,91199,91254,83550,83551,83552,83553,86617,86686,83039,90875,90954,85056,85142,85188,85234,84816,84817,86493,86495,86769,86771,91144,85307,85309,85404,85406,85455,85457,85506,85508,82624,83489,85096,83555,83556,86490,86766,85304,85401,85452,85503,86618,86687,85353,85355,83040,90876,90955,83350,83351,83352,83353,85054,85055,85140,85141,85186,85187,85232,85233,82812,82814,82885,82887,82958,82960,83332,83334,83342,83344,85350,83026,83027,90862,90863,90941,90942,82809,82882,82955,83329,83339,85094,85095,83549,83554,86491,86767,85305,85402,85453,85504))"
          }
        },
        {
          "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": 9,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "48.00",
              "eval_cost": "0.96",
              "prefix_cost": "105.93",
              "data_read_per_join": "25K"
            },
            "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": 9,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "2.40",
              "eval_cost": "0.96",
              "prefix_cost": "109.29",
              "data_read_per_join": "153"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}