SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '240b768c256a81a8b779bdb563d0a69a346cfbbd2349e9df5d18017638f41bed' 
  AND token = 'TexcC3qgs6m4jA2+FJXNtz/f3WoDa0HZv0OLNWw7U7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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