SELECT 
  a.modifier, 
  a.modifier_type, 
  a.commercial_dn, 
  a.same_as_option, 
  a.price_overrides, 
  a.base_cost, 
  a.variant_id 
FROM 
  cscart_product_option_variants a 
  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.variant_id IN (244279)

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "shared_option_variants",
      "access_type": "system",
      "possible_keys": ["PRIMARY", "company_id"],
      "rows": 0,
      "filtered": 0,
      "const_row_not_found": true
    },
    "table": {
      "table_name": "a",
      "access_type": "const",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["variant_id"],
      "ref": ["const"],
      "rows": 1,
      "filtered": 100
    }
  }
}

Result