SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a4e688232e2f25500946f45d55459c4d935ee75863fefed2df280cb263e0c47' 
  AND token = 'uVzYk2eiE2qJLPTfXVhcVyBEwtfYo1yXYx1ZBYtt+YM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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