SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 9859 
  AND lang_code = 'en'

Query time 0.00062

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 52 Using where

Result

feature_id variant_id value value_int
30 6221
127 5895
128 5899
129 5902
175 6237
170 6216
174 6234
169 0 0.680
171 6224
173 6228
174 6232
174 6233
178 6327
174 6235