You need to pass a date object and not a date string.
collection.findOne({last_updated: new Date('2014-01-22T14:56:59.301Z')},function(err, doc) {
The MongoDB driver will transform it into ISODate
:
{
"_id" : ObjectId("52dfe0c469631792dba51770"),
"last_updated" : ISODate('2014-01-22T14:56:59.301Z')
}
Check these questions: