SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4f44a58304522694d488bb2c8cd9a514361ead709edf78abc3fcc84ff1d6e9' 
  AND token = '9Ga6YNc0lxa5Db1Orx4AKxzTJR+4nJLOLh1Z7eHyRQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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