SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c67c0c5a5649164fc44bf00f50d4c7deffc659080097800f2e401c58f3c3998' 
  AND token = 'ENonnfVla5CqYbCC2l4pFliPj7uFhL6fEMxeb9wphKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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