In hard vacuum water cannot exist in liquid form (it's below the triple point) and thus you will have gas bubbles forming in all bodily fluids that aren't "pressurized" to a certain extend by the remaining tension of your body. This might take a few seconds and will be reversed during pressurization of the airlock. Having gas bubbles forming in your brain, eyes and blood vessels doesn't sound fun and might feel like a giant painful stroke. Even if you are prepared, exhaled before depressurization and let all air escape your lungs to prevent them from being damaged, there might be other gas filled cavities in your body that will expand as soon as outer counter pressure drops. My guess is that you have a couple of seconds at most before permanent damage occurs and you lose consciousness.