SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a20892948912f9e98ca0655d3805742fca801579121173be8e5de19dae74524' 
  AND token = 'AvYrp74Zxk/TBYWLYugv6CFdFIdzDy/PkLtnS3wmfJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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