SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4fc951520fc8905fd7cb5e3e64685b6ca6ab283f8b21e1a8c68a2cd97b234784' 
  AND token = 'oAHaNBKdfoW5eVMTdetyRtYfMKZadSbF01WZxEFbXvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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