SELECT 
  id_path 
FROM 
  categories 
WHERE 
  category_id IN (
    273, 291, 19100, 19102, 19105, 19215, 
    19247
  )

Query time 0.00052

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "3.17"
    },
    "table": {
      "table_name": "categories",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "p_category_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "category_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 7,
      "rows_produced_per_join": 7,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "2.47",
        "eval_cost": "0.70",
        "prefix_cost": "3.17",
        "data_read_per_join": "18K"
      },
      "used_columns": [
        "category_id",
        "id_path"
      ],
      "attached_condition": "(`goimagine`.`categories`.`category_id` in (273,291,19100,19102,19105,19215,19247))"
    }
  }
}