SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    30492, 30469, 30555, 30475, 30554, 30499, 
    30479, 30480, 30478, 30482, 30489, 
    30490, 30476, 30471, 30481, 30486, 
    30491, 30472, 30557, 30474, 30553, 
    30477, 30552, 30558, 30498, 30496, 
    30501, 30511, 30463, 30468, 30464, 
    30503, 30561, 30562, 30509, 30473, 
    30510, 30407, 30405, 30512
  )

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.56"
    },
    "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": 63,
      "rows_produced_per_join": 63,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "7.26",
        "eval_cost": "6.30",
        "prefix_cost": "13.56",
        "data_read_per_join": "163K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`maniamall_cscart`.`cscart_categories`.`parent_id` in (30492,30469,30555,30475,30554,30499,30479,30480,30478,30482,30489,30490,30476,30471,30481,30486,30491,30472,30557,30474,30553,30477,30552,30558,30498,30496,30501,30511,30463,30468,30464,30503,30561,30562,30509,30473,30510,30407,30405,30512))"
    }
  }
}

Result