SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '683ba80ad0a5598e66429a575da5b8fb7cf2b3e1e9a409ff2100e24d7b9e5f63' 
  AND token = 'Co4mgn6gh3FwjhDyCgiNYU4HZM1FmqnBJllIzi6Cps0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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