SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3707d50e56fa7254253930c969145e8887b17898742072d52427c1fc754afde1' 
  AND token = 'bSv0JtPQlPDu8RROAiOYQCobQLcfI9HSO1VrALaf3dk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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