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 
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') 
WHERE 
  cscart_products_categories.product_id IN (
    1096, 1098, 1095, 1078, 1086, 1099, 886, 
    884, 1055, 1056, 1057, 1058, 786, 789, 
    792, 699, 777, 774, 781, 1024, 1025, 
    1028, 1050, 1051, 1052, 1049, 1067, 
    1033, 1034, 1037, 1035, 1036, 1038, 
    1032, 1062, 1061, 1060, 1063, 1059, 
    1064, 1066, 612, 976, 978, 968, 971, 
    636, 969, 972, 977, 564, 848, 836, 834, 
    592, 590, 828, 842, 857, 879, 839, 868, 
    852, 873, 591, 859, 864, 875, 832, 1097, 
    679, 568, 578, 583, 573, 1040, 1072, 
    1022, 1023, 1054, 1053, 1070, 815, 811, 
    820, 819, 1100, 959, 952, 950, 951, 1079, 
    941, 948, 945, 953
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00205

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "115.33"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "11.19"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "ALL",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "rows_examined_per_scan": 125,
            "rows_produced_per_join": 5,
            "filtered": "4.00",
            "cost_info": {
              "read_cost": "29.49",
              "eval_cost": "1.00",
              "prefix_cost": "30.49",
              "data_read_per_join": "20K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`cscart`.`cscart_categories`.`storefront_id` in (0,1)) and ((`cscart`.`cscart_categories`.`usergroup_ids` = '') or find_in_set(0,`cscart`.`cscart_categories`.`usergroup_ids`) or find_in_set(1,`cscart`.`cscart_categories`.`usergroup_ids`)) and (`cscart`.`cscart_categories`.`status` in ('A','H')))"
          }
        },
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "cscart.cscart_categories.category_id"
            ],
            "rows_examined_per_scan": 12,
            "rows_produced_per_join": 11,
            "filtered": "18.65",
            "index_condition": "(`cscart`.`cscart_products_categories`.`product_id` in (1096,1098,1095,1078,1086,1099,886,884,1055,1056,1057,1058,786,789,792,699,777,774,781,1024,1025,1028,1050,1051,1052,1049,1067,1033,1034,1037,1035,1036,1038,1032,1062,1061,1060,1063,1059,1064,1066,612,976,978,968,971,636,969,972,977,564,848,836,834,592,590,828,842,857,879,839,868,852,873,591,859,864,875,832,1097,679,568,578,583,573,1040,1072,1022,1023,1054,1053,1070,815,811,820,819,1100,959,952,950,951,1079,941,948,945,953))",
            "cost_info": {
              "read_cost": "61.65",
              "eval_cost": "2.24",
              "prefix_cost": "104.14",
              "data_read_per_join": "179"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        }
      ]
    }
  }
}