Yes, you can use an open-top tort table for a one to two year old Russian tortoise. They do a lot better with cooler temps than other species of torts do. If your house gets very cold, you may have to cover or partially cover the table, but it can certainly be done and your tortoise would be ok in it.
The main reason for a cover is to hold in heat and humidity. Russians don't need as much of either as some other species. I house my year old russians in open tops, but they also have damp substrate, terra cotta water saucers sunk into the substrate, and humid hides to use if they wish. As long as you have a 95-100 degree basking spot in one area, it should be fine if the rest of the enclosure stays room temp.
The main thing to avoid is creating a beef jerky maker style of set up, where everything is all dry all the time. Smaller tortoises need help with hydration, and preventing water loss is one way to do that. Having a damp substrate for them to burrow into will also allow them to make their own little tiny micro-climate which will help with shell growth too.