SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81db478a0da1d8aee9e38fb5ae8018eed5681d1c9e1b50ea7d784373f0d37414' 
  AND token = 'kkEWwzDJTUlIXj/8H9jJc9QBmNX5P5nPD8/DD+CpTD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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