SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '83387254a6a7b2a991100bc6979f743d663e7bf757e92d4cf521ff64bb37c8bc' 
  AND token = 'C1hhHzdWJKrogqxAEhkMQDDwrFLWgrShSSxaY0RWoYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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