SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b19942ebea7fd896d407dccd03f3d138efe0aa062409ef19c69a4f776615281' 
  AND token = 'Yuf5gd+Ypa14qWUP8pliVTek7DigjenSZIa5Ou2PZu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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