SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9aef36793320dfc743a234f5339ceb9ef03460f2082f49a9b62158a7f600be67' 
  AND token = 'Uri4WYw1ios1cp5WPcFnFoObw88tOnG2RTjnSmmRMfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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