Running a queue worker without using cron tasks
Queue is processed by cron through core. You can also use Drush and Drupal Console to run queue items as well.

Drush:

drush queue:list to get the available queues.

drush queue:run to run a single item.

drush queue:delete to clear a queue.

Drupal Console:

drupal debug:queue to debug your queue.

drupal queue:run &lt;name-of-the-queue&gt; To run a single item.