Name: MyKey1._domainkey.mydomain.com

The field in which I insert the name of the record is too short compared to the value I insert:
MyKey1._domainkey.mydomain.com.
https://gyazo.com/ec2e7195f8c20e466a221b5fa726fa09

In fact it is cut. How to solve this issue?

Nothing to solve, that is correct. It does not show the domain name itself.