SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c9a8994c3eab9e21245c112794ae5eb70b604ecbfedfbe404bf98e18cf6f50a' 
  AND token = 'pQzQpxKrebMMKZvWFn8HPGkuWSE0uokoIt1MPmyxDa8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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