SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '500f4ab47b48a96db1331c54a964337f65a008f50df6a27122bfb085814bc794' 
  AND token = 'md1H/I6XC29XKU2geroJLIkbK6VIz9ZvCh+/LUJUqeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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