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SELECT 
  req_prod.required_id 
FROM 
  cscart_product_required_products as req_prod 
  LEFT JOIN cscart_products ON req_prod.required_id = cscart_products.product_id 
WHERE 
  req_prod.product_id = 241 
  AND cscart_products.status != 'D' 
GROUP BY 
  req_prod.required_id

Query time 0.00042

JSON explain

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