SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6efb466d52a167608893f06288ca2bfaa913b8a8c121c474f151e10e3caf36f8' 
  AND token = 'ln2gsrsVJlZUK/WMVMGsRNFnDyJ8yEeLG702YeJXgAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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