You'll want to use the format  object and set it to type:'date' .

"scale-x": {
    "max-items": 10,
    "min-value": 1433282400000,
    "transform": {
        "type": "date",
        "all": "%d.%m.%Y<br />%H:%i",
        "item": {
            "visible": false
        }
    }
},
"series":[
    {
        "values": [
            [1433282400000,25.68],
            [1433286000000,26.41],
            [1433289600000,26.52],
            [1433293200000,26.23],
            [1433296800000,25.77]
        ]
    },

Example: https://demos.zingchart.com/view/ONVC14XT 

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