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 = 2910 
WHERE 
  cscart_products_categories.product_id IN (
    356117, 359227, 359292, 350167, 350940, 
    352035, 352746, 354264, 350874, 351272, 
    353847, 354164, 356786, 359059, 350490, 
    354138, 355700, 356771, 358492, 350153, 
    350877, 354373, 350107, 353043, 355763, 
    356235, 356729, 356882, 354807, 355854, 
    349681, 350191, 351952, 352553, 357881, 
    359100, 350711, 351238, 351466, 351490, 
    351956, 353017, 353063, 355767, 350028, 
    351230, 353612, 356950, 357344, 358081, 
    353584, 355704, 358368, 353613, 351326, 
    351854, 353449, 355920, 358883, 351893, 
    351902, 351906, 354434, 356635, 356894, 
    358817, 353894, 355224, 358402, 354579, 
    355858, 357962, 350556, 353124, 352870, 
    353751, 357281, 357870, 352738, 356044, 
    358751, 357842, 359236, 350769, 352961, 
    354903, 357746, 350988, 351112, 352338, 
    352879, 353501, 353630, 354298, 357826, 
    353453, 354602, 358074, 350409, 352863
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00234

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 (356117,359227,359292,350167,350940,352035,352746,354264,350874,351272,353847,354164,356786,359059,350490,354138,355700,356771,358492,350153,350877,354373,350107,353043,355763,356235,356729,356882,354807,355854,349681,350191,351952,352553,357881,359100,350711,351238,351466,351490,351956,353017,353063,355767,350028,351230,353612,356950,357344,358081,353584,355704,358368,353613,351326,351854,353449,355920,358883,351893,351902,351906,354434,356635,356894,358817,353894,355224,358402,354579,355858,357962,350556,353124,352870,353751,357281,357870,352738,356044,358751,357842,359236,350769,352961,354903,357746,350988,351112,352338,352879,353501,353630,354298,357826,353453,354602,358074,350409,352863))"
          }
        },
        {
          "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')))"
          }
        }
      ]
    }
  }
}