SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2883963621e5b50a5a59d17a202e91929d108338198aac1a217cbd597ac8c65f' 
  AND token = 'z+rxRw2YJdLkZRRqv9wdFUZAAKKHQGxeFq0aWsbeavM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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