SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8d24e72ba49a666c0132d75d53c62519dce3c75733d0f1f7671a1b4f1d7defaa' 
  AND token = 'mhtn5k8VMZ6UMHvfn8KDQ4EHuyg2wkLHJIS2bZZ2KIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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