Twitter announced today that you can now use a USB security key, such as Yubikey, as part of the two-factor authentication process. It's the latest expansion of Twitter's verification support, which, as of last year, also includes third-party apps like Google Authenticator and Duo Mobile. By using a physical key, you'll be able to sign in securely even in situations where you can't or don't want to have a text message sent to your phone. Facebook, Google, Dropbox and others have added support for security keys in the past.
You can see how to set up your Twitter account for security key verification here.