SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bff5b145a57944e776bd7b4d64efbad088951ca6678817f0d9c8fd039314b38' 
  AND token = 'z5hVsqX4iKZK9TM8cEdqxAASkJflXiq8iXikWCjcAWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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