Submit form on enter without focus

I have a search form on my site and im wondering other peoples thoughts on this idea.

Essentially the flow goes like this user will type in search with the checkbox by default selected and click enter to submit the form. However if someone does not want the checkbox ticked they will lose focus on the form by unchecking it causing them to either A. click the magnifying glass or B. refocus on the form and click enter.

Would it be better to have enter no matter what submit the form regaurdless of focus?