How to check the security code of longka credit card?

The security code you said should be cvv code. This is on the back of your card. The signature column has a 7-digit number, and the last three digits are the security code. I can only read this on my card, but I can't find it by calling the bank. Because if the bank can inquire, it will definitely be unsafe for you, so there is no way to inquire through any channel.