SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '020e1cac3fdd9e260ddd03bd76a10f17d11a846559eb83a365b9fa517e72d341' 
  AND token = '6q2QdyqbSjd5U1UZs3sQNvpnWjgePm9gdcTEzyPvitQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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