title: Rails Redis expire method
body: <p>If i have a token which expires in 21 days</p>
  
  <pre><code>Rails.cache.write token, id, expires_in: 21.days
  </code></pre>
  
  <p>i am trying to write a method to check if the has expired or not. Kindly give me direction  </p>
  
  <pre><code>def check_token_expiry(token)
  
  end
  </code></pre>