Will locking a card after a charge is pending interfere with payment

So I was checking out at the grocery store self-check register just now and finished my purchase with a credit card.

When I turned around to go, there was a person standing right behind me. I almost jumped because they had made no noise and I was not expecting anyone there.

I've had cards hacked right after purchases at this store before and Im wondering if they were close enough to scan an nfc card in my wallet.

I'd like to lock my cards just in case, but the purchase I had just made is showing as "pending" in the card app.

Is it safe to lock a card with pending charges?