SELECT 
  feature_id 
FROM 
  cscart_product_features 
WHERE 
  feature_type = 'E' 
  AND status = 'A'

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.0629712,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_features",
          "access_type": "ALL",
          "possible_keys": ["status"],
          "loops": 1,
          "rows": 304,
          "cost": 0.0629712,
          "filtered": 100,
          "attached_condition": "cscart_product_features.feature_type = 'E' and cscart_product_features.`status` = 'A'"
        }
      }
    ]
  }
}