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SELECT 
  a.variant_id, 
  a.option_id, 
  a.position, 
  a.modifier, 
  a.modifier_type, 
  a.weight_modifier, 
  a.weight_modifier_type, 
  b.variant_name, 
  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 a.variant_id = b.variant_id 
  AND b.lang_code = 'se' 
  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 = 2 
WHERE 
  a.option_id IN (664, 665, 1218) 
  AND a.status = 'A' 
ORDER BY 
  a.position, 
  a.variant_id

Query time 0.00060

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	a	range	status,option_id,option_id_2	option_id	6		9	Using index condition; Using filesort
1	SIMPLE	b	eq_ref	PRIMARY	PRIMARY	9	mahm3t_cs443.a.variant_id,const	1	Using where
1	SIMPLE	shared_option_variants	eq_ref	PRIMARY,company_id	PRIMARY	7	mahm3t_cs443.a.variant_id,const	1

Result

variant_id	option_id	position	modifier_type	weight_modifier_type	variant_name
15537	664	10	A	A	75 x 220 x 1000 mm
22769	1218	10	A	A	Tegelröd (RAL 8004)
15539	665	11	A	A	Tegelröd
15538	664	20	A	A	65 x 220 x 1000 mm
22770	1218	20	A	A	Brun (RAL 8017)
15540	665	23	A	A	Brun
22771	1218	30	A	A	Kaffe brun (RAL 8019)
15541	665	34	A	A	Grafit
22772	1218	40	A	A	Röd-brun (RAL 8012)
15542	665	45	A	A	Svart
22773	1218	50	A	A	Röd (RAL 3004)
15543	665	56	A	A	Rödbrun (Kastanj)
22774	1218	60	A	A	Svart (RAL 9005)
15544	665	62	A	A	Röd
22775	1218	70	A	A	Antracitgrå (RAL 7016)
22776	1218	80	A	A	Grön (RAL 6020)