Getting user’s data, by custom field lookup (meta)

You may update your query like this :

get_users(
    array(
        'number' => 1,
        'count_total' => false,
        'meta_query'=> array(
            array(
               'key' => 'egt_session_key',
               'compare' => '=', 
               'value' => 'some_custom_field_data'
           )
       )
    )
)