SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b7c69a6da56a9b518d4565549eedbfc3ef849129c9561f71e03352079a37855' 
  AND token = 'oGqvb/mb/Mbt0AsHhf3Nq8/CNJk+jKHEcxbmC4o7YKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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