title: Laravel: Check if time + 4 hours has passed
body: <p>I store in my database a date format like this:</p>
  
  <pre><code>2017-02-22 16:55:40
  </code></pre>
  
  <p>I added it to my database like this:</p>
  
  <pre><code>Carbon::now();
  </code></pre>
  
  <p>I need to check if 4 hours passed since this date.</p>
  
  <p>How I can do this? I couldn't figure out how I can convert this format into Carbon or timestamp. </p>