SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12750ff28d58277cd9c92e8fab2bdd08351de34f08b965e1a61eba8985a5c1cf' 
  AND token = 'l5HK8Cqvrp8yvPzgeyZS5HYQHY+PkGzL4gdg5sJhyzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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