SELECT 
  category_id, 
  parent_id 
FROM 
  categories 
WHERE 
  parent_id IN(
    112, 123, 124, 114, 118, 113, 117, 116, 
    115, 110, 111, 119, 121
  )

Query time 0.00060

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "3.24"
    },
    "table": {
      "table_name": "categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 13,
      "rows_produced_per_join": 13,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "1.94",
        "eval_cost": "1.30",
        "prefix_cost": "3.24",
        "data_read_per_join": "34K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`goimagine`.`categories`.`parent_id` in (112,123,124,114,118,113,117,116,115,110,111,119,121))"
    }
  }
}