SELECT 
  category_id, 
  parent_id 
FROM 
  categories 
WHERE 
  parent_id IN(
    16544, 16545, 16547, 16543, 16557, 16554, 
    16548, 16549, 16551, 16550, 16555, 
    16559, 16558, 16556, 16552, 16560
  )

Query time 0.00059

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "5.08"
    },
    "table": {
      "table_name": "categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 22,
      "rows_produced_per_join": 22,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "2.88",
        "eval_cost": "2.20",
        "prefix_cost": "5.08",
        "data_read_per_join": "57K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`goimagine`.`categories`.`parent_id` in (16544,16545,16547,16543,16557,16554,16548,16549,16551,16550,16555,16559,16558,16556,16552,16560))"
    }
  }
}