SELECT 
  meta_description, 
  meta_keywords 
FROM 
  cscart_category_descriptions 
WHERE 
  category_id = 1 
  AND lang_code = 'ja'

Query time 0.00112

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_category_descriptions",
      "access_type": "const",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "category_id",
        "lang_code"
      ],
      "key_length": "9",
      "ref": [
        "const",
        "const"
      ],
      "rows": 1,
      "filtered": 100
    }
  }
}