SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '463068c46d12de50e743c3363745ef3200f934378706e759ce90c0ecc70f0242' 
  AND token = 'vGdrkFMQdD6Eq57b4QSTQurcZIXqECq0wZQ+nCU6t7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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