SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35d55f3a5b27edc56d1ed760d3898e21c9392a06e41c13971cef76e3b3c1789e' 
  AND token = 'iYi5KdnSip1yVAvuQINX9+BZvJXWw+oynFNFlywOj6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}