SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 574 
  AND lang_code = 'de'

Query time 0.00036

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_features_values ref lang_code,product_id,product_id_idx,product_feature_idx product_id 3 const 45 Using where

Result

feature_id variant_id value value_int
157 6145
159 6152
159 6150
30 123
127 5895
128 5899
129 5907
158 6147
149 0 5905400240160
159 6153
161 6188
178 6315