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SELECT 
  b.variant_name, 
  a.*, 
  IF(
    shared_option_variants.variant_id IS NOT NULL, 
    shared_option_variants.modifier, 
    a.modifier
  ) as modifier, 
  IF(
    shared_option_variants.variant_id IS NOT NULL, 
    shared_option_variants.modifier_type, 
    a.modifier_type
  ) as modifier_type 
FROM 
  cscart_product_option_variants AS a 
  LEFT JOIN cscart_product_option_variants_descriptions AS b ON b.variant_id = a.variant_id 
  AND b.lang_code = 'en' 
  LEFT JOIN cscart_ult_product_option_variants shared_option_variants ON shared_option_variants.variant_id = a.variant_id 
  AND shared_option_variants.company_id = 1 
WHERE 
  1 
  AND a.option_id IN (2) 
  AND a.status = 'A' 
ORDER BY 
  a.position, 
  a.variant_id

Query time 0.00042

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	shared_option_variants	system	PRIMARY,company_id				0	const row not found
1	SIMPLE	a	ref	status,option_id,option_id_2	option_id	6	const,const	5	Using index condition; Using where; Using filesort
1	SIMPLE	b	eq_ref	PRIMARY	PRIMARY	9	cscart_dev_4_16.a.variant_id,const	1	Using where

Result

variant_name	variant_id	option_id	position	modifier_type	weight_modifier_type	point_modifier_type	status
Small	6	2	10	A	A	A	A
Medium	10	2	20	A	A	A	A
Large	9	2	30	A	A	A	A
X Large	8	2	40	A	A	A	A
XX Large	7	2	50	A	A	A	A