SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e99f473829c908236ca76377ec465dbcc4b7a5dc0c514815f0be560d6070acf4' 
  AND token = '4SSaljrqkOKUulzRZmjtdUig3frv7wgyk4PSMTgAytE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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