Unique table version record

Unique table version record
Hello,
I am using a table record to store informations about database dump,I
use this table :

CREATE TABLE dump_version(
count BIGINT unsigned NOT NULL DEFAULT 0,
timestamp TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
DEFAULT 0
);
And I added a record (INSERT INTO dump_version () VALUES();) that I
modify each time I dump the database.
The only problem is that I can't ensure that this table will contain
only a single record, is that a way to ensure a king of 'UNIQUE' record
or something?
Thank you in advance.
Regards.
Nassim.