Hey there, Marko.
Unfortunately it depends on your laptop and BIOS/UEFI if you'd be able to boot from an express card SSD. I'd recommend that you check the User Manual of the laptop, or better yet - get in touch with the manufacturer's customer support for more help.
You could also check that thread for further reference: http://www.tomsguide.com/answers/id-1638709/install-windows-expresscard-based-ssd-laptop.html.
Hope that helps.
Boogieman_WD