SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '729c03e92f622bdb08ff279f3c0a0aa6826ce23c40f95fc9559f1ef5f4db7a96' 
  AND token = 'k6SXDCuolk1NpoLZ1o7PfS0cPUFNjb3EpniU2nvmyjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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