Likely a modern invented name combining Kay and the suffix -ston.
Kayston is a contemporary American creation, likely formed by blending the phonetic 'Kay' sound with the popular 'ston' or 'ton' suffix found in English surnames. While it lacks a singular historical etymology, it follows the linguistic pattern of names like Kingston or Colton, suggesting a 'settlement' or 'town' association.
Less common today
Kayston isn't in the latest US Top 1000. It last peaked at #6,324 in 2017.
US births per 5-year period, 1990βpresent (SSA data).