SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '830e8fde458d11e3858e57b9253026d988c1067e662e3d81a52f661ac7587893' 
  AND token = 'tBNTztB++M8YDgOh5zvsHuLosojLpK7IG6Yohsyzluw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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