SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '885921fbf25d942dbec1edb983608d699fbe1955cb7e710ffd87504cf1f3fc62' 
  AND token = 'RWboFz3NIpT716TCgsQe2MXsEsuU2yBCgNj14yjpRk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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