SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a860408859aad9e36eb302abc92a37983d31ba63e904f4591123d3ff1aed0902' 
  AND token = 'HbUdgt4/iFd+7yXDN2MKVOD8xXF5v/e2KBrz0qBB0jM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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