You're not alone. I'm older than you are. Theoretically I'm too old to be employed as a programmer. Yes, I've lost out on a lot of jobs because they asked trivia questions about some language or computer science concept I hadn't thought of in years. I prefer to look at it as their loss. It seems to me that the emphasis on memorization of abstruse detail tends to favor younger people. Us older folks don't remember quite as quickly but we have more experience in solving problems. Therefore, those interviews show a fundamental misunderstanding of the needs of the job. In other words, you might be better off avoiding those places anyway.
All that said, I have been almost continuously employed for a dozen years or so. Periods of unemployment are short, and when I work the pay is high. While I may fail to answer the random BS questions at several interviews in a row, I get far more interviews than people I know in other lines of work, and wind up employed again after far shorter periods of time. Sometimes it's freelance or contract work but even those are paying excellent money for programmers these days.
I guess it's a trade off. You have to endure a lot of frustration to get to the satisfying and successful bits. Don't give up hope! (But do see if there's a side project that can tide you over. Programming skills can support many baskets to put your eggs in)