SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '32781be2088e6f14d8bcbb731a3e176323e237d09693908ef7b6c976205a65dd' 
  AND token = '5zmFlhfUKwZEKp5PXUokG0nX5uoqwVRW5hWgdp1JR2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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