Yes you can.
Instant Log In can be turned off for a specific login, or for all your logins in the True Key app. Once Instant Log In is turned off, your username and password information will still be entered into the fields, but you'll need to click the log in button to access the site. Here's how to do it:
1) Click the pencil icon on the login you'd like to disable Instant Log In.
2) Click the Advanced tab on the top right. Then, under the Parameters tab, disable Instant Log In.