SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a340132eec10d0743a632155622f8232367e091653081898f4d333d689090c8' 
  AND token = 'u0iylDCI1XzrL3f7TKFLqv1QCxmk/9bhsn9oK7QVz/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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