Capital One is paying 5% on an 11 month CD today. Based on the rates on longer terms, it looks like they’re thinking rates have peaked.
So back to your question: 2% on your mortgage is likely not tax deductible. But you are taxed on the interest on your CD…if you have a decent income, you could be paying a third of your earned interest to the feds. If you’re in a high tax state, subtract that too. So this won’t be much of a money maker for you. Being liquid is nice, though. Having a paid for house is nice as well.
Note: Keeping money in the stock market instead of paying down your house will likely have a better profit margin for you and as long as you hold your investments longer than a year, they’re taxed as long term capital gains and not ordinary income.