SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '479d6386ea75c5f778bac18ae8277cd18f1ba986cfe14e800119c31275733440' 
  AND token = 'op+YgOl0VZ4ZdgTQY1BgtkOohp1Is+4EFmu+VRjmvPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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