That's a bit outside of my normal cruising range so I can't comment specifically about Granby, but I'm sure there must be a sizable liquor store in Enfield, which is just down the road. If you go ten minutes south on 91 to South Windsor or Manchester, you can go to M&R Liquors. They have a good selection and decent prices. The South Windsor store might be closer on the map, but it might be easier and/or a little faster to go to the Manchester location. I live on the other side of the state, but I drive through that area very frequently and have shopped at both locations.
206 Buckland Rd
South Windsor, CT 06074
120 Tolland Turnpike (Rte. 83)
Manchester, CT 06042
Here's their Whiskey list. I wish they'd break it up into Scotch/Bourbon/Other instead of just one long list, but still you can see they have a nice selection of both Scotch and Bourbon.