SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '648fd02fab1236aa619b0279709a8de8df425ddd2baf59034df7d75041821634' 
  AND token = 'xSIZQVKUelcpM8EpdTJRFxEndknvvK5lIGEocrpn3g8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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