In order to turn that into a date, you need to do the following in MySQL:
SELECT FROM_UNIXTIME(event_time) FROM MY_TABLE
or if you like a date nicely formatted, then:
SELECT DATE_FORMAT(FROM_UNIXTIME(event_time), '%d/%m/%y %h:%i%p') FROM MY_TABLE
NB: This assumes that your event_time is in seconds. If you are using Java, for example, then you will have probably stored your timestamp in millisconds (as kicked out by System,currentTimeMillis() ) so in this instance, MySQL will rather rudely just return NULL.
To fix this, simply divide by 1000 first as follows:
SELECT FROM_UNIXTIME(event_time/1000) FROM MY_TABLE
or if you like a date nicely formatted, then:
SELECT DATE_FORMAT(FROM_UNIXTIME(event_time/1000), '%d/%m/%y %h:%i%p') FROM MY_TABLE