SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6b9355845cbd28927caba97c9c7419f49a1e81339b7c69bbdf469f33add48c9' 
  AND token = 'arte8R337xm9grUNpBneCyryXpWkPkdS5KcOWCwNIAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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