SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e28fea20558c3a6bea02dff2b1ff9d14ced3d90ce24857084b2c4da58b7349d' 
  AND token = '1QL9BIMdfpaLGs0KPR3TjAAs57ug0UWfQIUssjgF9PA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}