SELECT 
  a.variant_id, 
  a.position, 
  a.modifier, 
  a.modifier_type, 
  a.weight_modifier, 
  a.weight_modifier_type, 
  a.status, 
  a.yml2_variant, 
  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, 
  b.variant_name 
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 = 'ru' 
  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 
  a.option_id = 35 
ORDER BY 
  a.position

Query time 0.00099

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "a.position",
        "table": {
          "table_name": "a",
          "access_type": "ref",
          "possible_keys": ["option_id", "option_id_2"],
          "key": "option_id",
          "key_length": "3",
          "used_key_parts": ["option_id"],
          "ref": ["const"],
          "rows": 8,
          "filtered": 100,
          "attached_condition": "a.option_id <=> 35"
        }
      }
    },
    "table": {
      "table_name": "b",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["variant_id", "lang_code"],
      "ref": ["orbit_cscart_orbit_cscart.a.variant_id", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(b.lang_code = 'ru')"
    },
    "table": {
      "table_name": "shared_option_variants",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY", "company_id"],
      "key": "PRIMARY",
      "key_length": "7",
      "used_key_parts": ["variant_id", "company_id"],
      "ref": ["orbit_cscart_orbit_cscart.a.variant_id", "const"],
      "rows": 1,
      "filtered": 100
    }
  }
}