SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a535171aee434670aab5e2905a3387f74c7573b5cc1a36e2b5d844d3022f3fb6' 
  AND token = '0zLS62T09JMr6LC9XQoHn/fFzDKTyFmjvYGEpJpGwiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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