SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38fc4379adeacfeb142d090789f0a99ffa3e1aa9bc171d66a28c57b25e050380' 
  AND token = 'hXtdoyPcZDhcYg+rpR/ppEI3YgXz351dp5v9dj9uDWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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