SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e764fa9acfb4b3b6c7a1b7b2fe9c5dcf990dcda225f675094297d252c9634cc' 
  AND token = '7Q1Js/QmY1k/sZXiYFxSmQsGzAoHdAlge/iaMjtMFM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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