How to extract the pub part from a X509 Subject Public Key Info?

Question

So I have a certificate in pem format (mycert.pem), from which I only need to extract the public key.

openssl x509 -in mycert.pem -pubkey -noout gives me a public key. However, it seems to be the base64 encoded string of the entire subject public key info.

Subject Public Key Info:
    Public Key Algorithm: id-ecPublicKey
        Public-Key: (256 bit)
        pub: 
            04:6e:af:3c:7d:4c:a3:1a:81:f0:ae:14:45:16:67:
            38:5b:09:4d:9e:55:f8:e2:f2:ba:e4:55:28:f6:31:
            d8:25:c3:2d:f9:a2:d5:62:ba:eb:17:5f:1d:ad:99:
            50:e4:a6:bd:eb:9b:44:18:0f:72:ae:bd:fb:87:1f:
            82:dd:98:be:25
        ASN1 OID: prime256v1
        NIST CURVE: P-256

However, I'm only interested in the "raw" public key part pub:

04:6e:af:3c:7d:4c:a3:1a:81:f0:ae:14:45:16:67:
38:5b:09:4d:9e:55:f8:e2:f2:ba:e4:55:28:f6:31:
d8:25:c3:2d:f9:a2:d5:62:ba:eb:17:5f:1d:ad:99:
50:e4:a6:bd:eb:9b:44:18:0f:72:ae:bd:fb:87:1f:
82:dd:98:be:25

How can I extract (dynamically!) the relevant information? It is important to have an approach that works for any certificate, not just the example presented.

My implementation is in php, so ideally I'll find a solution using phpseclib or openssl functions. But understanding how it works with openssl via the command line, for example, also helps. Thank you.