from django.db.models import Count

Model.values('pickup_plan_id').annotate(picked_count=Count('pickup_plan_id')).filter(picked_count__lt=2)

# SELECT
# 	`model`.`pickup_plan_id`,
# 	COUNT(`model`.`pickup_plan_id`) AS `picked_count`
# FROM
# 	`model`
# WHERE
# 	`model`.`pickup_id` = 870001
# GROUP BY
# 	`model`.`pickup_plan_id`
# HAVING COUNT(`model`.`pickup_plan_id`) < 2
# ORDER BY NULL