SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9559b4cd69945a0b365b39a8078b1ad14cc4ab62f897acf4f60d7718bed0881' 
  AND token = '6TuT/NLPd75eLDrRnd+worJtxNEe/0u6UftC8ApKsw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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