SELECT 
  category_id, 
  parent_id 
FROM 
  categories 
WHERE 
  parent_id IN(
    16898, 16901, 19243, 15647, 19244, 15649, 
    16896, 19241, 16895, 15646, 15648, 
    19242, 16897, 19240, 19232, 15645, 
    15644
  )

Query time 0.00056

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "6.28"
    },
    "table": {
      "table_name": "categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 28,
      "rows_produced_per_join": 28,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "3.48",
        "eval_cost": "2.80",
        "prefix_cost": "6.28",
        "data_read_per_join": "73K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`goimagine`.`categories`.`parent_id` in (16898,16901,19243,15647,19244,15649,16896,19241,16895,15646,15648,19242,16897,19240,19232,15645,15644))"
    }
  }
}