I'm also a software engineer in my 40s who has not had trouble getting jobs. My answer is yes, I definitely keep current. Right now I'm working on Gatsby in TypeScript. 10 years ago it was Phonegap and native iOS. 20 years ago it was PHP and a bit of Mac software in Objective-C. By staying current I can negate the main objection that employers have to older developers, which is that our skills are outdated and we're unwilling to learn new things. It's more fun too!