SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c176cc2351b980f4c1449516f88041abefabe8a321311b4adbc1698478d356e9' 
  AND token = 'mHR9JMPKqABMS4mhGHmQg5bWJkcJAx0hOY/QXAG4k8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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