SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3db34850f84074ae0a71eee0fb1f7b5c176d495b3267de47902a1bef31ecab7' 
  AND token = 'WTIIZDO9HFuFH8tVpVmchxKyGIgleYqBDw8gUZGaG4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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