SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8715908e1ae7ee8c4848f2a0dd7731d035f18077b85d8bbf85ff3227ff0f251e' 
  AND token = 'PQRvpRfNGbsYJBPADRrXYqdZNMa0ayX0V9nxT+l5WLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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