SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfdce413733fab7890e7dccf4602a8a250593f62f53db232956237d10b535104' 
  AND token = 'n0KRXYvaC8HycSNZtLNOzf3YhQFw99WBv0mIMazUZRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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