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SELECT 
  f.feature_id, 
  f.purpose, 
  p.product_id, 
  p.parent_product_id, 
  g.id, 
  g.code 
FROM 
  ushop_product_variation_group_features AS f 
  INNER JOIN ushop_product_variation_groups AS g ON f.group_id = g.id 
  INNER JOIN ushop_product_variation_group_products AS p ON f.group_id = p.group_id 
WHERE 
  p.product_id IN (
    337, 321, 323, 327, 324, 332, 341, 333, 
    335, 339, 334, 336, 340, 343, 338, 342
  )

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}