SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b1d7a627be5de11ca03b631eb7265f773a995e85d955fbcfeddbe3c20ede203' 
  AND token = 'oTUFhIfyRmrvvE9dustkH3+oT9fe0+YhgLW0HguotME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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