SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '258f1b3523b64ef54d9831657bd254a3d25e2a3d7801cbd0ae92af97bcdaa4a8' 
  AND token = 'v1w6vtvfU/tAwVIe+wbDpB6Dm22aDGj2K1oYQ8qRuB0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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