SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7897afcd6c8cfbaa8bdc6439b2bfbd6c198796bccc153b9820f1cb73deb83cd' 
  AND token = 'PKLValkyYDFdpOxLD+b8jzK5I9uz1O+bccvvZ5ivuIA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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