SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9ff1454bcfb6da2f593e465838fc3e71e6d23ffd6ade73ba1e0b7298a37129a1' 
  AND token = 'VTF/ImmU8Q12S5tQ7zstpJhaByYe+UO9vVOmChoqauk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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