SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b678f584e8423d59fd8de98e306d4439e52ef38bd35208319762f020a1335108' 
  AND token = 'VpKAH0TjF3IKPglzCEwidyd3n6JH7hFe4eyLf3FQomE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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