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SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 8894 
  AND lang_code = 'en'

Query time 0.00069

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	115	Using where

Result

feature_id	variant_id	value	value_int
23	103
42	145
30	240
23	101
21	96
19	5989		0.600
24	107
134	5962
127	5895
128	5899
129	5902
20	6059		1.000
124	0	5702326178764
178	6308
152	6118
152	6116
152	6106
152	6105
152	6102
152	6101
152	6100
152	6097
152	6096
149	0	5702326178801
152	6095
152	6094
152	6092
152	6093
152	6090
152	6089
22	99