Lenovo Thinkpad X230 BIOS embeds a whitelist of WLAN cards. If a card is not in the whitelist, it is rejected by the laptop.
Are there any 802.11ac cards that would work on Lenovo Thinkpad X230?
No, but that wouldn't stop you from installing one.
The official whitelist for Lenovo Thinkpad X230 contains only 4 wireless NICs ("WLAN"s, "wireless cards"), none of which is 802.11ac:
BIOS for Lenovo Thinkpad X230 can be replaced with an "unlocked" version, overriding the whitelist completely and allowing you to install any physically compatible WLAN card, including 802.11ac ones. The path isn't that easy, but if you really want the feature, here is a list of steps: