SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db7592adea4a7c7a879c9698e2506b3a0d9601f8013b4ceff544d282033fc2f5' 
  AND token = '9LbHBlM1Nr8KZ/1JGoXBtuHd7UoW1QrKHuds46CW92Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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