SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8243cdd703e58e4571ed596ed677de8984d4a428308da1d031e18a144acfe81f' 
  AND token = '8vGHCsDOj8VFGq51Eq5ZMwF9TM/TnvJNLS5ojEwE8Bw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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