CDs and money market funds are secure investments that preserve principal. If you want a better yield, you have to take on some risk.
You stated that you don't trust the stock market at your age and probably won't live long enough to recover losses from a down-turn. If that's truly the case, you can stop reading this answer now.
Investment grade preferred stocks currently offer about a 5+ pct yield and have much lower risk than common stocks. With some periodic swapping, you can bump the yield up several percentage points. Even more when there's an interest rate cycle which isn't now.
There are three risks with Pfd stocks. First, there’s the underlying soundness of the company. Companies like Citibank, Capital One, Public Storage, Goldman Sachs, JP Morgan Chase, Wells Fargo and various utilities like Entergy and Nextera are so not likely to go bankrupt. But they can get into trouble (see the 2008 GFC).
Of more significance is the interest rate risk, unless they are floating rate Pfds. Like bonds, Pfd share price drops when rates rise. That’s not a problem if you’re going to hold them long term for the income but will be an issue if you are going to need the principal for other expenses, at the wrong point in the rate cycle.
Lastly, most Pfds are callable in 5 years. If called and rates are lower, you won't be able to replace your higher income positions and your yield will drop.
As a concrete example of swapping, I bought a Pfd on Monday that pays a quarterly dividend of 38 cents on 1/29 (6.03% yield). I sold it 4 days later for a gain of 35 cents and then bought another Pfd with the proceeds. Why wait up to 3 months for a similar amount (6 weeks in this case) as well as take the risk that share price could drop, taking away my 35 cent gain? A year ago, I bumped a sit and do nothing yield of 6% to just over 12%. Pretty decent for the fixed income portion of my portfolio.
The disadvantage of swapping is that you give up Qualified Dividend Income status (QDI) which is a lower tax rate. I have no problem with that because the end result is still far better at the higher tax rate.
If this sounds appealing, there's one fly in the ointment. With the recent drop in interest rates, too many Pfds have risen above par and because they are now callable (5 years has passed since their issue date), there's a potential capital loss if called. Because of this, pickings are slim out there. Don't buy Pfd stocks that are much above par (issue price) and are callable in the near future.