SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6aff5df1ce002716bb57e9dd96d1b47f7d38e7ffd693b20ec85f1b55008ce343' 
  AND token = '+w+A6afM3jLKLBjfXYbiFRxrDJXIq94goMnUznV6CvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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