SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '720693e347a1eaf415510c89e477485e46602a12fcc1b41af3c3a323c3d36b7b' 
  AND token = 'lItEeEgYPhNN6wrFJvbAv5TIhXrRI2OPnALm0F8qKyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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