SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94f85b6aec7d117e3c4a47e47644dae66d47dee252fe574131c9a4289adb39bd' 
  AND token = '4BN7WGmYHw0RDf2bWDNjXZByUy+uwhLgkH9Xr7KIl5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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