While I don't recall ever seeing it done in a residential structure it is quite common to install floor hatches into a crawl space in schools, hospitals or other commercial structures.

The least expensive method is to install a metal frame & metal hatchcover howeve they do make a metal metal frame with a hatchcover that is formed as a shallow pan so they can install the same ceramic material on the cover to match the floor which then only leaves the outline of the frame and hatchcover plainly visible.

You would probably need to consult a masonary contractor supply house to find these covers.

They also offer these type of hatche frames and covers in Brass which would provide a better finished appearance as well as a much greater resistance to corrosion.