SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5546c9f12cf298c1c9b20d87f49d9532aa236774f84a92028ed73dbe7845288' 
  AND token = '2nV2/TGIt+rbYWb04KFKsFvMXCjTzbtaZIl/yqONCuI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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