SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3b11445a98269843cdddb6c0084e4ae4fab1bb3e396a2662f8116ed99b3eed9e' 
  AND token = 'mZJAICBYDGe1R/zAy6OB4zccflQW0r9RXXsSPS70Qig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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