SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73f2508fbc907d222237b807c6f014b935010b9d857d1abe7698bc762a9f2535' 
  AND token = 'JA/7XV/ktpu8qNwhvvk+gAOskjB7rfZpLCzilOTxZRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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