SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    34391, 34553, 36071, 34703, 41289, 36073, 
    1569, 1337, 6559, 1334, 1169, 1231, 
    1117, 1321, 1297, 1021, 1022, 6563, 
    1149, 5109, 1328, 5466, 13058, 30005, 
    7180, 37603, 13060, 1019, 30002, 12963, 
    28750, 7382
  )

Query time 0.00061

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "8.25"
    },
    "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": 38,
      "rows_produced_per_join": 38,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "4.45",
        "eval_cost": "3.80",
        "prefix_cost": "8.25",
        "data_read_per_join": "98K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`maniamall_cscart`.`cscart_categories`.`parent_id` in (34391,34553,36071,34703,41289,36073,1569,1337,6559,1334,1169,1231,1117,1321,1297,1021,1022,6563,1149,5109,1328,5466,13058,30005,7180,37603,13060,1019,30002,12963,28750,7382))"
    }
  }
}

Result