SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '727776920c271452198e0556446851550966f3fbde1b8b8bdde2272c940017b9' 
  AND token = 'POkxULw1E6eUbP4Oxs+ot+FlVK+hfIyuZxJEZZvQuOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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