Currently new API ShaderUtil.GetPassKeywords returns an array of LocalKeywords, which is not efficient enough for searching specific enabled local keyword.
To wokaround it the array have to be recreated to hashset.

For example:
// Get all contained local keywords by this pass
var m_ContainedLocalKeywords = new HashSet<LocalKeyword>();
var keywords = ShaderUtil.GetPassKeywords(shader, snippetData.pass);
foreach (var kw in keywords)
m_ContainedLocalKeywords.Add(kw);