SELECT 
  a.variant_id, 
  a.option_id, 
  a.position, 
  a.modifier, 
  a.modifier_type, 
  a.weight_modifier, 
  a.weight_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 = 'ja' 
WHERE 
  a.option_id IN (20, 25) 
  AND a.status = 'A' 
ORDER BY 
  a.position, 
  a.variant_id

Query time 0.00004

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "a.position, a.variant_id",
        "table": {
          "table_name": "a",
          "access_type": "ref",
          "possible_keys": ["status", "option_id", "option_id_2"],
          "key": "status",
          "key_length": "3",
          "used_key_parts": ["status"],
          "ref": ["const"],
          "rowid_filter": {
            "range": {
              "key": "option_id_2",
              "used_key_parts": ["option_id"]
            },
            "rows": 5,
            "selectivity_pct": 15.625
          },
          "rows": 32,
          "filtered": 15.625,
          "index_condition": "a.`status` = 'A'",
          "attached_condition": "a.`status` <=> 'A' and a.option_id in (20,25)"
        }
      }
    },
    "table": {
      "table_name": "b",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["variant_id", "lang_code"],
      "ref": ["smscrm_edev.a.variant_id", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(b.lang_code = 'ja')"
    }
  }
}