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SELECT 
  cscart_vendor_plan_descriptions.*, 
  cscart_vendor_plans.*, 
  manual_rating.rating AS manual_rating 
FROM 
  cscart_vendor_plans 
  LEFT JOIN cscart_vendor_plan_descriptions ON cscart_vendor_plan_descriptions.plan_id = cscart_vendor_plans.plan_id 
  AND cscart_vendor_plan_descriptions.lang_code = 'tr' 
  LEFT JOIN cscart_manual_rating AS manual_rating ON manual_rating.object_id = cscart_vendor_plans.plan_id 
  AND manual_rating.object_type = 'vendor_plan' 
WHERE 
  cscart_vendor_plans.plan_id = 4 
ORDER BY 
  position asc 
LIMIT 
  0, 1

Query time 0.00020

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows
1	SIMPLE	cscart_vendor_plans	const	PRIMARY	PRIMARY	4	const	1
1	SIMPLE	cscart_vendor_plan_descriptions	const	PRIMARY	PRIMARY	10	const,const	1
1	SIMPLE	manual_rating	const	PRIMARY	PRIMARY	102	const,const	1

Result

plan_id	lang_code	plan	description	status	position	is_default	price	periodicity	commission	fixed_commission	products_limit	revenue_limit	vendor_store	categories	storefronts	usergroups	lowers_allowed_balance	grace_period_to_refill_balance	manual_rating
4	tr	Platinum		A	40	0	0.00	onetime	10.00	0.00	100000	0.00	1						0