title: Perform a task in 15 minutes from now in Rails
body: <p>I'm creating a Rails application that let users book tickets for an event.</p>
  
  <p>Once the user selects the ticket he wants to buy, he has 15 minutes to complete the checkout, otherwise the ticket will be released and can be booked by someone else.</p>
  
  <p>How can I "block" the ticket for 15 minutes and make it available again after 15 minutes?</p>