SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'be3286a5858e222fb69d59182bf47c849b0235868474a1168b55464b0f694e84' 
  AND token = 'iqgyWRzZWQZc8JMxa5lW0Xr0QAQVBsgkjMDOa27JyFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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