SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    1166, 1167, 1218, 2718, 1181, 6853, 1006, 
    6991, 1176, 8779, 1220, 1040, 1194, 
    1193, 1140, 1195, 7344, 1139, 1161, 
    7129
  )

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "7.14"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 32,
      "rows_produced_per_join": 32,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "3.95",
        "eval_cost": "3.20",
        "prefix_cost": "7.15",
        "data_read_per_join": "83K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`maniamall_cscart`.`cscart_categories`.`parent_id` in (1166,1167,1218,2718,1181,6853,1006,6991,1176,8779,1220,1040,1194,1193,1140,1195,7344,1139,1161,7129))"
    }
  }
}

Result