SELECT 
  f.feature_id, 
  f.purpose, 
  p.product_id, 
  p.parent_product_id, 
  g.id, 
  g.code 
FROM 
  cscart_product_variation_group_features AS f 
  INNER JOIN cscart_product_variation_groups AS g ON f.group_id = g.id 
  INNER JOIN cscart_product_variation_group_products AS p ON f.group_id = p.group_id 
WHERE 
  p.product_id IN (341, 346, 351, 286, 287, 288)

Query time 0.00601

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE p ALL PRIMARY,idx_group_id 35 Using where
1 SIMPLE f ALL idx_group_id 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE g eq_ref PRIMARY PRIMARY 3 cscart_dev_4_16.p.group_id 1

Result

feature_id purpose product_id parent_product_id id code
549 group_catalog_item 286 0 11 PV-1C4130471
549 group_catalog_item 287 0 11 PV-1C4130471
549 group_catalog_item 288 0 11 PV-1C4130471
549 group_catalog_item 341 0 13 PV-9318A163F
549 group_catalog_item 346 0 13 PV-9318A163F
549 group_catalog_item 351 0 13 PV-9318A163F
548 group_variation_catalog_item 341 0 13 PV-9318A163F
548 group_variation_catalog_item 346 0 13 PV-9318A163F
548 group_variation_catalog_item 351 0 13 PV-9318A163F