Buy a piece of plain trim with a really flat profile and enough depth to rout out a groove for the cord in the back of it. Run cord inside and glue to ceiling and wall down to the outlet. Be sure to have a switch installed on the cord at a convenient height for you to turn it on. Paint to match the ceiling and wall colors.I have done this; it works. Not beautiful, but it works and is not ugly.

I would see how much adding the electrical box over your table would cost. That would definitely be the most attractive solution.