Receive all used slugs
I already found a solution. I just created a simple query:

SELECT content.elementId entryId, title, uri
FROM `craft_content` content
JOIN craft_elements elements ON elements.id = content.elementId
JOIN `craft_entries` entries ON entries.`id` = content.`elementId`
JOIN `craft_elements_i18n` `elements_i18n` ON elements_i18n.elementId = 
elements.id