It's actually easier than one would think. Firefighters do this all the time when they rescue unconscious victims from a building ... so much so that it is actually called a fireman's carry.
https://en.wikipedia.org/wiki/Fireman's_carry
I wouldn't call it easy, but it is definitely doable.
I am familiar with fire mans carry as I have done many times over the years in wrestling and martial arts. However, an unconscious body is far different than a dead body where rigor mortis has set in. I remember 2 of us trying to move a German Shepard that had passed on at a friends house and that was extremely difficult.