SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b6445d9ffae9d2fc6c75ba07bedae9051d834234ee6804f86a46566b92e5399' 
  AND token = 'ntXhkBV0Xd02MWRCrCYz89+55SaQNPA9qjU0qYd6lEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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