SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c9b7731dd07700601236b5bf798031f160a865a1890f2c9f1db3bb2a4727047' 
  AND token = '7dBItSOCzXMSflrs1o/TFw1oBjCw8EJjMt2T+AfWjgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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