SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1298578aa83e53f14a5601fd9203cbdafecb786801fc77b6e93a8fda6f5a9422' 
  AND token = 'HcJot2F3tqPfImr6yJBVz2/Eljz44DbsCxDWJ4WthKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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