To avoid sub query use HAVING same query will get total count and take that count and apply with HAVING like WHERE condition

SELECT
  ul.id,
  ul.device_type,
  ul.device_token,
  COUNT(cl.lead_id) AS total_leads
FROM
  custom_leads AS cl
LEFT JOIN
  user_login AS ul ON ul.id = cl.lead_cre_user_id
WHERE
  cl.lead_from = 'dealer-app' AND ul.user_type = '21' AND ul.user_category = 'Dealer' AND ul.sub_type = 'Org'
GROUP BY
  cl.lead_cre_user_id
HAVING
  total_leads >= 10 AND total_leads <= 35