SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76c6496d7c9fc7defda037005419ae6f91ce7562242bc440c999bca98439d326' 
  AND token = 'otoeW5hIMzXjEoYW8L6Xzd0NlZBeIdHCwtMZZFjn4p0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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