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 = 7194 
WHERE 
  cscart_products_categories.product_id IN (
    88904, 90824, 90825, 87232, 87233, 87237, 
    87238, 87242, 87243, 87247, 87248, 
    84251, 84256, 87580, 87595, 87610, 
    88791, 84250, 84255, 87578, 87579, 
    87593, 87594, 87608, 87609, 88151, 
    88153, 88789, 88790, 87653, 87667, 
    87674, 87681, 87702, 87710, 87711, 
    87724, 87725, 87652, 87658, 87666, 
    87672, 87673, 87679, 87680, 87686, 
    87701, 87707
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00116

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "27.52"
    },
    "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": 48,
            "rows_produced_per_join": 48,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "5.08",
              "eval_cost": "4.80",
              "prefix_cost": "9.88",
              "data_read_per_join": "768"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`nuie_scalesta_net`.`cscart_products_categories`.`product_id` in (88904,90824,90825,87232,87233,87237,87238,87242,87243,87247,87248,84251,84256,87580,87595,87610,88791,84250,84255,87578,87579,87593,87594,87608,87609,88151,88153,88789,88790,87653,87667,87674,87681,87702,87710,87711,87724,87725,87652,87658,87666,87672,87673,87679,87680,87686,87701,87707))"
          }
        },
        {
          "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": 2,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "12.00",
              "eval_cost": "0.24",
              "prefix_cost": "26.68",
              "data_read_per_join": "6K"
            },
            "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": 2,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "0.60",
              "eval_cost": "0.24",
              "prefix_cost": "27.52",
              "data_read_per_join": "38"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}