As the most recent viruses like Looky and the others came with a file that needs to be executed and then some parts are loading the the actual malicious program that encrypt your files on the pc I have to say it is possible!
What you can do (beside making backups) is at your pc you log in as an another user (of course not admin!!) (if Win 7 or later) where as well is a mt4/5 is installed and there you can load and execute it. Then wait and see and let your antivirus search.
This provides not an absolute security (buzzword memory overflow and gaining admin rights) - but it's a bit better than just loading installing and executing.