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 = 7211 
WHERE 
  cscart_products_categories.product_id IN (
    87640, 87876, 88506, 88507, 88510, 87987, 
    90828, 87632, 88561, 87637, 90827, 
    87938, 87941, 87997, 88026, 87781, 
    87882, 87988, 88047, 88048, 88050, 
    88051, 88052, 88053, 88054, 87990, 
    87961, 87875, 87937, 87950, 87959, 
    88798, 90826, 87952, 88004, 87998, 
    88000, 87881, 88031, 87948, 88702, 
    88749, 87945, 87942, 87964, 88029, 
    88018, 88021
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00187

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "78.06"
    },
    "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": 137,
            "rows_produced_per_join": 137,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "14.01",
              "eval_cost": "13.70",
              "prefix_cost": "27.71",
              "data_read_per_join": "2K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`nuie_scalesta_net`.`cscart_products_categories`.`product_id` in (87640,87876,88506,88507,88510,87987,90828,87632,88561,87637,90827,87938,87941,87997,88026,87781,87882,87988,88047,88048,88050,88051,88052,88053,88054,87990,87961,87875,87937,87950,87959,88798,90826,87952,88004,87998,88000,87881,88031,87948,88702,88749,87945,87942,87964,88029,88018,88021))"
          }
        },
        {
          "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": 6,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "34.25",
              "eval_cost": "0.69",
              "prefix_cost": "75.66",
              "data_read_per_join": "17K"
            },
            "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": 6,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "1.71",
              "eval_cost": "0.69",
              "prefix_cost": "78.06",
              "data_read_per_join": "109"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}