This Dua is regarded as a special dhikr of masnun dhikr-

لَا إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيْكَ لَهُ، لَهُ الْمُلْكُ، وَلَهُ الْحَمْدُ، وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيْرٌ

Laa 'ilaaha 'illAllahu wa'hdahu laa shareeka lahu, lahul-mulku wa lahul-hamdu, wa Huwa 'alaa kulli shay'in Qadeer.

None has the right to be worshipped except Allah, He is alone, without any partner, to Him belong all sovereignty and praise, and He is over all things omnipotent. Many hadiths are narrated about benefit of this dhikr. Many authentic reports commanded us to to recite this dua in every morning and evening 1 or 10 or 100 or 200 times, After every obligatory prayer, and generally without any time restriction.

Reference: Bukhari: 3293