SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7699969a07ee2dd9571380e362174b407e639de2ddaceda170be8bfee16cb3b' 
  AND token = 'ZszTIMbIp4LPLJknQBWv5Q+s6cHvwNuMMA4mGxvvIso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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