You can identify all leads who are owned by "a" queue by creating a list where SFDC Type = lead and Lead owner is empty.
Right now there is no out of the box way to create a list of leads owned by a specific queue(s), you would need to do something like create a custom field in SFDC to copy the queue name
You may wish to vote for this https://community.marketo.com/MarketoIdeaDetail?id=08750000000HRddAAG
Cathal