You don't say, but I'll presume you are traveling inside the US. First, the box MUST fit under the seat or in the overhead. Depending on which airport you are departing from, you won't even be allowed to get into the security line if it won't fit in the sizing grid. Don't count on an overhead, either. Depending on the equipment the airline is using, it can be very tight. Also, unless you have boarding priority, you will likely find most of the overheads stuffed by the time you actually board. Next, you may be asked to remove the table from the box and prove that it will power up. That's a brand-new regulation for cell phones, tablets and computers for international travelers entering the US on non-stop flights, but the TSA being what it is, expect confusion at best and substantial intimidation at worst on anything they don't immediately understand no matter where you're going. Last, the airlines really do mean it now when they say one carry-on and one personal item and they can make you reconfirm box size at the gate. If the gate attendants don't like it for whatever reason, you table will go to gate check and there isn't a damn thing you can do about it. That means you have to make sure the table is well-packed and you have indelible labels on the box that can't easily be removed.
Good luck!
Good luck!