create table t2(a int) encryption='keyring';
mysql> alter table t2 encryption_key_id=9999999999;
Query OK, 0 rows affected (0.83 sec)
Records: 0 Duplicates: 0 Warnings: 0

mysql> select current_key_id from information_schema.innodb_tablespaces_encryption where name = 'test/t2';
----------------

----------------

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1 row in set (0.00 sec)

It simply prints garbage value.