SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5a30f2dd9d68034f3940b9296c23d25d566c096c846f0c5b4aa65f1fe584315' 
  AND token = 'KQ0kM/ZfjeWIZIeG97xQsWlfJCqdRmk5vscRIcEPr0E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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