SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69d43bbe3a171e2ed2c8f2218af62329788b6bcab9eda4d421e30faa8dba5988' 
  AND token = 'AueZn/isuh6htjPlmSC65JStkVGYJaXklGaK9SEqm+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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