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 = 7165 
WHERE 
  cscart_products_categories.product_id IN (
    95035, 95036, 95037, 95038, 95039, 95040, 
    95041, 95042, 95043, 95044, 95045, 
    95046, 95047, 95048, 95049, 95050, 
    95051, 95052, 95053, 95054, 95055, 
    95056, 95057, 95058, 95059, 95060, 
    95061, 95062, 95063, 95064, 95065, 
    95066, 95067, 95068, 95069, 95070, 
    95071, 95072, 95073, 95074, 95075, 
    95076, 95077, 95078, 95079, 95080, 
    95081, 95082, 95083, 95084, 95085, 
    95086, 95087, 95088, 95089, 95090, 
    95091, 95092, 95093, 95094, 95095, 
    95096, 95097, 95098, 95099, 95321, 
    95322, 95323, 95324, 95325, 95326, 
    95327, 95328, 95329, 95330, 95331, 
    95332, 95333, 95334, 95335, 95336, 
    95337, 95338, 95339, 95340, 95341, 
    95342, 95343, 95344, 95345, 95346, 
    95347, 95348, 95349, 95350, 95351
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.01988

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "86.69"
    },
    "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": 96,
            "rows_produced_per_join": 96,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "9.89",
              "eval_cost": "9.60",
              "prefix_cost": "19.49",
              "data_read_per_join": "1K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`nuie_scalesta_net`.`cscart_products_categories`.`product_id` in (95035,95036,95037,95038,95039,95040,95041,95042,95043,95044,95045,95046,95047,95048,95049,95050,95051,95052,95053,95054,95055,95056,95057,95058,95059,95060,95061,95062,95063,95064,95065,95066,95067,95068,95069,95070,95071,95072,95073,95074,95075,95076,95077,95078,95079,95080,95081,95082,95083,95084,95085,95086,95087,95088,95089,95090,95091,95092,95093,95094,95095,95096,95097,95098,95099,95321,95322,95323,95324,95325,95326,95327,95328,95329,95330,95331,95332,95333,95334,95335,95336,95337,95338,95339,95340,95341,95342,95343,95344,95345,95346,95347,95348,95349,95350,95351))"
          }
        },
        {
          "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": 96,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "24.00",
              "eval_cost": "9.60",
              "prefix_cost": "53.09",
              "data_read_per_join": "1K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        },
        {
          "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": 4,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "24.00",
              "eval_cost": "0.48",
              "prefix_cost": "86.69",
              "data_read_per_join": "12K"
            },
            "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')))"
          }
        }
      ]
    }
  }
}