SELECT 
  * 
FROM 
  ushop_currencies 
WHERE 
  auto_update = 'Y' 
  AND next_update < 1771276470

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "0.81"
    },
    "table": {
      "table_name": "ushop_currencies",
      "access_type": "ALL",
      "rows_examined_per_scan": 3,
      "rows_produced_per_join": 1,
      "filtered": "33.33",
      "cost_info": {
        "read_cost": "0.71",
        "eval_cost": "0.10",
        "prefix_cost": "0.81",
        "data_read_per_join": "128"
      },
      "used_columns": [
        "currency_id",
        "currency_code",
        "after",
        "symbol",
        "coefficient",
        "is_primary",
        "position",
        "decimals_separator",
        "thousands_separator",
        "decimals",
        "status",
        "modifier_rate",
        "modifier_type",
        "modifier_sign",
        "auto_update",
        "next_update"
      ],
      "attached_condition": "((`marketplace`.`ushop_currencies`.`auto_update` = 'Y') and (`marketplace`.`ushop_currencies`.`next_update` < 1771276470))"
    }
  }
}