SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b40f78cd6f9a5a4a56eebabe39a2a6bfb4620a77f3a00bd01283f74832e41f7' 
  AND token = 'zL7+YM4QSnopV9NCjbcsJtRPl9dmllH5sB8PqlBVqpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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