mysql でテーブルの更新時刻は、information_schema DB の tables テーブルの UPDATE_TIME で取得することができます。
mysql> select table_schema, table_name, update_time from information_schema.tables where table_schema = 'DB名' and table_name = 'テーブル名'\G
+--------------+------------+---------------------+
| table_schema | table_name | update_time |
+--------------+------------+---------------------+
| DB名 | テーブル名 | 2011-05-27 20:52:59 |
+--------------+------------+---------------------+
1 row in set (0.01 sec)
mysql> select table_schema, table_name, update_time from information_schema.tables where table_schema = 'DB名' and table_name = 'テーブル名'\G
+--------------+------------+---------------------+
| table_schema | table_name | update_time |
+--------------+------------+---------------------+
| DB名 | テーブル名 | 2011-05-27 20:52:59 |
+--------------+------------+---------------------+
1 row in set (0.01 sec)
