SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fac9e151b70864ec9659a8aad1651a4f0f908ad8d7068f2a2d2f66cbb4d356a' 
  AND token = '5G8DcQltPr9ZdJ1rOsnm2bkK8WsyMGn/SouxrhjTZ2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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