title: How to get all redis keys close to expire
body: <p>I want to make the key live longer if some condition met.</p>
  
  <p>What I think is if I can query all the keys close to expire (like 10 minutes to expire), then I can do the query-check-activate intervally.
  I seached but not found any clue, if you know how to achieve it, please tell me.
  Any help will be highly appreciated!</p>