SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9726658fb155725a45d86500c22473e0d003fcb42c48aaa8974064347341e0e1' 
  AND token = 'AsZ1mCrvpgMiEMN2NP+MPrxOKmikndenoZ5e5upnQBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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