SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5a291878fed4fa9282bdae6097e917faecfa24d33b3e81c345a698389b62581' 
  AND token = 'dmp/N5DuJVbKzCYSJH2VzToaSZtWCMjM5DwHmoXhquY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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