SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad00cfa2772e0450f10f449b78e50489ac534aaf7837bddb813b4ac347ba3a39' 
  AND token = 'Em9Zv1qf0xMUfr2DnKrZ0+RZUVNlGPB6OCPpBJmiThg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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