SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '956db973c69cd5e370003655735155cb966e71ce9c670781b66796204e39c1d8' 
  AND token = 'wbHxIgZdpDT0wlzdW7wZ2XmPB5+UvPloTSPMiFcwI7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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