SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '921651e38c0ea5eefbbfa6cf34363633a9675f6e839886ce194d2f928df51037' 
  AND token = 'zg7ElMadptsibD3C+vbrCEHdWmYWUiB/nX8K0zK9YzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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