SELECT 
  product_id, 
  feature_short_desc 
FROM 
  cscart_ab__short_desc_from_features_values 
WHERE 
  product_id IN (
    21343, 21344, 21345, 21346, 21347, 21348, 
    21349, 21350, 21351, 21352, 21353, 
    21354, 21355, 21356, 21357, 21358
  ) 
  AND lang_code = 'en' 
  AND storefront_id = 1

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_ab__short_desc_from_features_values",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 16,
      "filtered": 100,
      "attached_condition": "cscart_ab__short_desc_from_features_values.storefront_id = 1 and cscart_ab__short_desc_from_features_values.product_id in (21343,21344,21345,21346,21347,21348,21349,21350,21351,21352,21353,21354,21355,21356,21357,21358) and cscart_ab__short_desc_from_features_values.lang_code = 'en'"
    }
  }
}