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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4947fad3a9f2bd768a26fe7187cde8bdf1302ae0a7946e494dbde30c4264a4af' 
  AND token = 'fu5ZSXDf5tlJf2XJBl/Upyq6bbLopt5OcEN94ZqQRss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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