SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'e245b3306fc2809124697de8fc9b1e2fd04297ce64eaab05f945a85718701ab6' 
  AND token = '64de/4t/71imGfD47AWX3ZaRkceAkIAhRfH7LGGPwt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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