SELECT 
  feature_id, 
  feature_type 
FROM 
  cscart_product_features 
WHERE 
  feature_id IN (
    18, 595, 549, 598, 599, 596, 602, 597, 
    605, 548, 15, 16, 17
  )

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "14.41"
    },
    "table": {
      "table_name": "cscart_product_features",
      "access_type": "ALL",
      "possible_keys": [
        "PRIMARY"
      ],
      "rows_examined_per_scan": 55,
      "rows_produced_per_join": 12,
      "filtered": "23.64",
      "cost_info": {
        "read_cost": "11.81",
        "eval_cost": "2.60",
        "prefix_cost": "14.41",
        "data_read_per_join": "15K"
      },
      "used_columns": [
        "feature_id",
        "feature_type"
      ],
      "attached_condition": "(`danishecarter_31jan`.`cscart_product_features`.`feature_id` in (18,595,549,598,599,596,602,597,605,548,15,16,17))"
    }
  }
}