CSS: Hover effect only for filled table cells

I have a table consisting of cells with or without content. Now, I want to implement some hover effect that should only be active when there is content within the <td> element:

CSS

td:hover {
   background-color: red;
}

HTML

<td>
  <p>I am content</p>
</td>
<td>
  <input type="text" value="I am also content" name="test" />
</td>
<td>
  // No hover effect here!
</td>

In this example, the hover effect should only be applied to the first and the second td-cell. The empty third cell should not have any hover color.

Thank you for your help.