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 = 266 
WHERE 
  cscart_products_categories.product_id IN (
    431225, 431483, 431058, 431207, 431430, 
    431475, 431496, 431086, 431479, 430986, 
    431036, 431282, 431351, 431391, 431450, 
    431223, 431059, 431227, 431437, 430716, 
    431294, 431492, 430996, 431278, 431296, 
    431396, 431435, 431460, 435511, 431413, 
    430777, 431367, 431221, 431261, 431323, 
    431331, 431485, 431276, 431258, 431307, 
    431312, 431348, 431471, 431382, 431448, 
    431095, 431477, 431499, 381714, 431214, 
    431310, 431375, 431449, 431266, 431299, 
    430728, 431491, 431347, 431366, 431436, 
    431441, 431075, 431418, 431489, 430709, 
    431228, 431265, 431321, 431400, 431363, 
    431486, 431189, 430670, 431206, 431370, 
    431374, 431388, 387053, 430774, 430779, 
    431209, 431232, 431256, 431257, 431379, 
    387048, 430710, 431179, 431404, 431445, 
    430668, 431293, 431277, 431286, 431462, 
    431317, 431473, 431476, 431320, 431390
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00339

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "281.15"
    },
    "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": 100,
            "rows_produced_per_join": 100,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "21.15",
              "eval_cost": "20.00",
              "prefix_cost": "41.15",
              "data_read_per_join": "1K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`webmarco`.`cscart_products_categories`.`product_id` in (431225,431483,431058,431207,431430,431475,431496,431086,431479,430986,431036,431282,431351,431391,431450,431223,431059,431227,431437,430716,431294,431492,430996,431278,431296,431396,431435,431460,435511,431413,430777,431367,431221,431261,431323,431331,431485,431276,431258,431307,431312,431348,431471,431382,431448,431095,431477,431499,381714,431214,431310,431375,431449,431266,431299,430728,431491,431347,431366,431436,431441,431075,431418,431489,430709,431228,431265,431321,431400,431363,431486,431189,430670,431206,431370,431374,431388,387053,430774,430779,431209,431232,431256,431257,431379,387048,430710,431179,431404,431445,430668,431293,431277,431286,431462,431317,431473,431476,431320,431390))"
          }
        },
        {
          "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",
              "webmarco.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 100,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "100.00",
              "eval_cost": "20.00",
              "prefix_cost": "161.15",
              "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": [
              "webmarco.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 5,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "100.00",
              "eval_cost": "1.00",
              "prefix_cost": "281.15",
              "data_read_per_join": "29K"
            },
            "used_columns": [
              "category_id",
              "usergroup_ids",
              "status",
              "storefront_id"
            ],
            "attached_condition": "((`webmarco`.`cscart_categories`.`storefront_id` in (0,1)) and ((`webmarco`.`cscart_categories`.`usergroup_ids` = '') or find_in_set(0,`webmarco`.`cscart_categories`.`usergroup_ids`) or find_in_set(1,`webmarco`.`cscart_categories`.`usergroup_ids`)) and (`webmarco`.`cscart_categories`.`status` in ('A','H')))"
          }
        }
      ]
    }
  }
}