How do I find the time my Apple Card was used?

If you are referring to an Apple Gift Card that is not possible. If you suspect your Apple Gift Card was compromised see the link below...

If you can't redeem your Apple Gift Card, App Store Card, or App Store & iTunes Gift Card - Apple Support

Have to correct myself now.

There may be a time stamp if you open a specific purchase in the Wallet App for the card. It will tell you the date and time at the top just under the total, and place.

Tap on the Apple Card, then on a specific purchase in the list.

Sorry, there is no user accessible time stamp for the card usage. You only have the date.