SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd614140b17c4cda60bb829d79751b4a9f12e15b6686d343efdf6ace1ec76c934' 
  AND token = 'I8SxdGbMOtZHy4Zf25Tg/3/+WwwUXW3dgtGD9IVWh4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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