Immediately lock and/or delete your card through your Viva Wallet App or Account Interface. Locking and/or deleting your Viva Wallet card will make it inoperative in your Google Pay App.
If you find your device after you have locked your card, you can simply unlock your card from you Viva Wallet App or User interface and use Google Pay.
If you have deleted your card, you can either create a free new digital card from your Viva Wallet app/Account Interface or order a new physical debit card and add it to Google Pay as before.