SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ccf504562dff382d8ec9b65a167689b07c924e5b97b4891884810227dd5156f3' 
  AND token = 'VLhnTQszzjdlAtqbd8ufleq7JG9lXhMUVcdnaUC7iAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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