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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 (
    21981, 19965, 21982, 20033, 21983, 21057, 
    21984, 20398, 22341, 22345, 22346, 
    22347, 22348, 22349, 20404, 21593, 
    20402, 21594, 20403, 21595, 20400, 
    21596, 20399, 21597
  )

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}