SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15cbbce7e1e29f7bbc4e4b9391d9ff355d5ca46f0222bb91e737b462e9a49635' 
  AND token = 'kaKcb3i2wIXwav9paDvUVhdsUEGhWN/VwKnaGUUjxq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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