SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad500647e0d0bd65065da1b3615d8b4dbf4c4caead737387706afa88cab11012' 
  AND token = '4Fh5zi8TyWErDKLpI7CssQpy4W59rhcdMwiat/PXR2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}