SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4a204ab42608d592f33ad47b0d8bf10d6943a08afc18ed1ff643debb77e5854' 
  AND token = 'GBDlI5Q92svaLRpR2HkDkxtwAku+MkrXrtYiWw4NxYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}