SELECT 
  ushop_vendor_plan_descriptions.plan_id, 
  plan 
FROM 
  ushop_vendor_plan_descriptions 
WHERE 
  lang_code = 'en'

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "2.32"
    },
    "table": {
      "table_name": "ushop_vendor_plan_descriptions",
      "access_type": "ALL",
      "rows_examined_per_scan": 18,
      "rows_produced_per_join": 1,
      "filtered": "10.00",
      "cost_info": {
        "read_cost": "2.14",
        "eval_cost": "0.18",
        "prefix_cost": "2.32",
        "data_read_per_join": "1K"
      },
      "used_columns": [
        "plan_id",
        "lang_code",
        "plan"
      ],
      "attached_condition": "(`marketplace`.`ushop_vendor_plan_descriptions`.`lang_code` = 'en')"
    }
  }
}