SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6acfe63957d282866b018231035b3d1ef343defa785e69edc18a6af89fef2024' 
  AND token = 'iCml42goncO+7MPDijFSPHdWv3dT1d9RERxS0YqD2YE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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