SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5eb1e2f3f58f63c132c50b87a3fb7543ce7d1c4275324bc6b722b192b708690f' 
  AND token = 'wl2LENWIau9bNGcXGzdZWrqYzCjBl/ZgwqevfkO5x34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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