SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59b2193fb63a13fca5fe520c947e76186c3ed89140072f109e30ce296ad45adb' 
  AND token = 'nwfA5coFcGS7j2JgNZGhfFCBjBvPZcwj28NxyJdCYCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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