SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28bc6f4fd3d105754f32b7ef009fb850edd94ed56b882a6ccb5d51e69023359c' 
  AND token = 'FTpjDp0eUfZAd6K4OkwUF0wm7sw+zJFmu5cPXUU+g44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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