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 = 7171 
WHERE 
  cscart_products_categories.product_id IN (
    82632, 83529, 87294, 87295, 85103, 86131, 
    86154, 86639, 86708, 85850, 85851, 
    85860, 85861, 85089, 85175, 85221, 
    85267, 85100, 83558, 83563, 85061, 
    85147, 85193, 85239, 87314, 87315, 
    87326, 87327, 87338, 87339, 87350, 
    87351, 89769, 85129, 86132, 86155, 
    86640, 86709, 86175, 86176, 86198, 
    86199, 85101, 85840, 85841, 87302, 
    87303, 85087, 85173, 85219, 85265, 
    86173, 86174, 86196, 86197, 82834, 
    82836, 82907, 82909, 82980, 82982, 
    83394, 83396, 83404, 83406, 85127, 
    86514, 86515, 86790, 86791, 85059, 
    85145, 85191, 85237, 82831, 82904, 
    82977, 83391, 83401, 89808, 89810, 
    89860, 89862, 89932, 89934, 91498, 
    91500, 86129, 86130, 86152, 86153, 
    85099, 85296, 85298, 85393, 85395
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00240

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "109.29"
    },
    "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": 192,
            "rows_produced_per_join": 192,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "19.53",
              "eval_cost": "19.20",
              "prefix_cost": "38.73",
              "data_read_per_join": "3K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ],
            "attached_condition": "(`nuie_scalesta_net`.`cscart_products_categories`.`product_id` in (82632,83529,87294,87295,85103,86131,86154,86639,86708,85850,85851,85860,85861,85089,85175,85221,85267,85100,83558,83563,85061,85147,85193,85239,87314,87315,87326,87327,87338,87339,87350,87351,89769,85129,86132,86155,86640,86709,86175,86176,86198,86199,85101,85840,85841,87302,87303,85087,85173,85219,85265,86173,86174,86196,86197,82834,82836,82907,82909,82980,82982,83394,83396,83404,83406,85127,86514,86515,86790,86791,85059,85145,85191,85237,82831,82904,82977,83391,83401,89808,89810,89860,89862,89932,89934,91498,91500,86129,86130,86152,86153,85099,85296,85298,85393,85395))"
          }
        },
        {
          "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": 9,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "48.00",
              "eval_cost": "0.96",
              "prefix_cost": "105.93",
              "data_read_per_join": "25K"
            },
            "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": 9,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "2.40",
              "eval_cost": "0.96",
              "prefix_cost": "109.29",
              "data_read_per_join": "153"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}