SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20a8b3d7c7a74cdbf9af2cf07b3b93b2f1dd45fd90b6ecdf109e5bf651da0d47' 
  AND token = 'Kx4pOngq7yvkfebaeHZjme1U9DjSxPLiQFQaIhiPE4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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