With 2-Step Verification (also known as two-factor authentication), you add an extra layer of security to your account in case your password is stolen. After you set up 2-Step Verification, you’ll sign in to your account in two steps
Why I can't find the "Security Key" options on the setting?
Make sure you already turn on the Two-factor-authentication
Before you can set up a security key, you need to first turn on either Text message or Authentication app as one of your two-factor-authentication methods.