SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08c4ef5d8e9470584616eed53d4cb491edc6295f963d5171aaa078dc6952a0c6' 
  AND token = 'OshPHZi1xIc55hAh5yokHP/FLy5+qJlH/HM/JsYb78A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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