It took me 7 years instead of the 4 to get bachelor's. I have no excuse other than I slacked off and skipped class/played video games. How to explain if an interviewer asks me why it took me so long?
If they don't bring it up, say nothing.
If they do bring it up, say that personal circumstances required you to take more time than is typically necessary to finish your degree. Don't elaborate. Most employers won't dig further into it than that.
It's kind of a tough one to reliably spin into a positive light, so I'd suggest trying not to go into it.
I likewise took unusually long to finish my bachelors (6 years) and nobody, nobody, has ever asked why. Your transcript may reflect your "slacking off", which, combined with your graduation time, may prompt the question. My recommendation is to always tell the truth. If I were in your shoes my response would be along the lines of "Honestly, I didn't take my studies seriously when I started college. I was immature, and was not as devoted to studying as I should have been. I paid the price for this, and boy did I learn my lesson."
Remember, telling the truth does not mean you give all the gory details.
In case they ask about it, I think you could use my answer given in How to explain above average PhD time in a job interview. Use the long time it took you to finish college as an argument for your grit, determination and perseverance.