Verifique a natureza padrão do campo de data e hora no SOLR
DatefieldSOLR
Converta seu valor de data e hora com a seguinte função mysql
SELECT id,DATE_FORMAT(created_at,'%Y-%m-%dT%TZ') as created_at,... from table
SELECT id,DATE_FORMAT(created_at,'%Y-%m-%dT%TZ') as created_at,... from table
