添加到多个表时的Mysql当前时间戳

I have 3 tables that I will be adding to on a certain action. All have current_timestamp field in them. How do I ensure that the time on all three of these tables are exactly the same ? I am using laravel, and I would like to know if using DB:Transaction ensures this.

If not, then what else can I do ?

Save the timestamp in a variable and then use that to update/insert in all three tables e.g.

$current_timestamp = time();

NOTE : i am using PHP's default time function.