the max date you can get is 2038, check the year 2038 problem for more information about this issue. Now to solve the problem -- as @Mike suggested -- you can use DateTime objects, consider the following example:
$date =new DateTime("2090-11-29 05:00:00");
echo $date->format('Y-m-d H:i:s'); //will output 2090-11-29 05:00:00
and you can set the format as you wish and there are enough examples found in the php documentation Also settimezone function for datetime object