What product to use for sealing a wood tv stand
Polyurethane will be a durable and glossy finish and will really bring out the beauty in the stain you used. I can tell you, however, it will take at least a couple weeks to fully cure and stop smelling. 

The key to a great finish is to use many thin coats.  Brushing it on can be the most economical way, but its important to maintain a wet edge so you have a smooth application.  Thin coats.  An easier way to apply poly is to spray it on.  You can buy it in spray cans for a little higher price per unit.  Again just remember to make very thin coats.  You do not want any drips or else you are laying it on way too thick.  Let it dry until its just tacky and apply another coat.  You shouldn't need to sand in between coats if you are applying them in succession before the layer before totally cures, and looks smooth.