SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a8555297e32592b87f861709ee752833b064f45e927631d944bda8c24ba0a9d' 
  AND token = 'JO3SnduTvR3erpo+qxxWOhi2OyCtwRFjDFBvUi/UDvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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