SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '596238d13320a37ef357d432fe6243d6a25aea3992f5eeaedbbc1d96c84ac39a' 
  AND token = 'AISSJsbaAKkk5ERG6GyxyXTGJ83uQGI8EKFAB+Z/WPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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