SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '16496957c538b10f4cff283d9ef34e5a800623992b61d9be626c72a93d12a883' 
  AND token = '+l7KuV1xiz963k/P8Ejjt+wL27LNSethIsW0uVpU/L4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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