SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8037f4cfbdbff624498f1f3c3ddac321ae491973027b32aec7df4df21646a95b' 
  AND token = 'u8LlDKzTBzL+ZDTj5uWNZK8avHUrpL7FBCH3+bS0TKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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