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 = 7210 
WHERE 
  cscart_products_categories.product_id IN (
    94831, 94839, 94840, 94841, 94843, 94850, 
    94851, 94852, 94853, 95309, 95315, 
    95316, 95318, 95319, 95365, 95366, 
    95367, 95368, 95369, 95370, 95371, 
    95372, 95373, 95374, 95375, 95376, 
    95377, 95736, 95756, 95757, 95758, 
    95759, 95760, 95761, 95762, 95763, 
    95768, 95769, 95770, 95771, 95772, 
    95773, 95774, 95775, 95776, 95777, 
    95778, 95779, 95789, 95821, 95822, 
    95823, 95824, 95825, 95826, 95827, 
    95828, 95830, 95831, 95867, 95868, 
    95869, 95870, 95871, 95872, 95873, 
    95874, 95875, 95876, 95877, 95878, 
    95879, 95880, 95881, 95882, 95883, 
    95884, 95889, 95891, 95892, 95895, 
    95896, 95897, 95898, 95899, 95900, 
    95901, 95902, 95903, 95904, 95905, 
    95906, 95907, 95908, 95909, 95910
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00181

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "144.50"
    },
    "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": 254,
            "rows_produced_per_join": 254,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "25.75",
              "eval_cost": "25.40",
              "prefix_cost": "51.15",
              "data_read_per_join": "3K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`nuie_scalesta_net`.`cscart_products_categories`.`product_id` in (94831,94839,94840,94841,94843,94850,94851,94852,94853,95309,95315,95316,95318,95319,95365,95366,95367,95368,95369,95370,95371,95372,95373,95374,95375,95376,95377,95736,95756,95757,95758,95759,95760,95761,95762,95763,95768,95769,95770,95771,95772,95773,95774,95775,95776,95777,95778,95779,95789,95821,95822,95823,95824,95825,95826,95827,95828,95830,95831,95867,95868,95869,95870,95871,95872,95873,95874,95875,95876,95877,95878,95879,95880,95881,95882,95883,95884,95889,95891,95892,95895,95896,95897,95898,95899,95900,95901,95902,95903,95904,95905,95906,95907,95908,95909,95910))"
          }
        },
        {
          "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": "63.50",
              "eval_cost": "1.27",
              "prefix_cost": "140.05",
              "data_read_per_join": "33K"
            },
            "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": "3.18",
              "eval_cost": "1.27",
              "prefix_cost": "144.50",
              "data_read_per_join": "203"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}