SELECT 
  feature_id 
FROM 
  cscart_product_features 
WHERE 
  feature_id IN (
    948, 949, 979, 951, 984, 975, 972, 946, 
    945, 977, 961, 947, 943, 968, 959, 974, 
    956, 944
  ) 
  AND feature_type = 'E'

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "31.57"
    },
    "table": {
      "table_name": "cscart_product_features",
      "access_type": "ALL",
      "possible_keys": [
        "PRIMARY"
      ],
      "rows_examined_per_scan": 133,
      "rows_produced_per_join": 1,
      "filtered": "1.35",
      "cost_info": {
        "read_cost": "31.21",
        "eval_cost": "0.36",
        "prefix_cost": "31.57",
        "data_read_per_join": "2K"
      },
      "used_columns": [
        "feature_id",
        "feature_type"
      ],
      "attached_condition": "((`danishecarter_25_march`.`cscart_product_features`.`feature_id` in (948,949,979,951,984,975,972,946,945,977,961,947,943,968,959,974,956,944)) and (`danishecarter_25_march`.`cscart_product_features`.`feature_type` = 'E'))"
    }
  }
}