SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91d7f73dd4aa8c6f72eb994ce992799b23f5681e9ea8802a3c479e6c919d93b0' 
  AND token = 'WWE469u1R2gKmxYqKLIBiFMRGyfzgMpQvjAghxRitTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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