SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a0b79a67efb65f98464914dde43ed890bae25df5f518de2e21264edcd795031' 
  AND token = '5f3aFyDEkGo0gzFoYG9pywWuCigIFNaFf1JPInzFtv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}