SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3e60c9f969149f4965e5c9c7dcaa687c894827063babc0156b9be8894844af6' 
  AND token = 'IYxsWWJlXjPrYoXIJcPhs5JKQbhGgRHgDI93X8hXnjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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