SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df96c763b6054705c182790e33e40acff942ed8b7ae87e34351829c21e71bacd' 
  AND token = 'HCuJYuIXNkB3CXusknKatN166IuYciWFr+rF4nTweBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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