Set a state value.
drush state-set
key : The state key, for example "system.cron_last".
value : The value to assign to the state key. Use '-' to read from STDIN.
Sets a timestamp for last cron run.
drush state-set system.cron_last 1406682882 --format=integer
Set a key to a complex value (e.g. array)
php -r "print json_encode(array('drupal', 'simpletest'));" | drush state-set --format=json foo.name -