SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c5d2a1be3210ad48bcc70a00e5c14e22529e813da160c441df0794b67cf59d9' 
  AND token = 'JtwiBKU/0GVNrZbQKE+9OElBy891apQFtDbmjEzOIoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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