The last couple places I left, I had offers up to a year or two before leaving but weighing cost-benefit, stayed at that time.
It's better to have the option than not. And interviewing is truly not that much work. You don't have to be perfect. The less you need the job, the less the interview process should stress you. We call this "opportunistic interviewing".
You can emphasize to the recruiter/HR/interviewer when pressed that - actually I'm happy where I am at the moment, but I am always up for a conversation and this sounded like it could be an interesting opportunity.
You may find companies even respond more favorably in the interview process to you when you are somewhat aloof in this manner. You will also make connections with companies who may touch base from time to time to see if now is a better time to make the jump.
This is infinitely better than having zero leads and feel like your life is going to hell before you even start looking.