SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d5e954159cb1a43f7c1e462a4916d8bffac821767cf171c4d9b10a493a5d99c' 
  AND token = 'myyFfHZAWTmEDxVvpk6eU0u2Wf89fYAtoDMYPk+h4bY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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