SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a6c6b3b281c14ffb46e64a4551f14cac1d04e48fa8b4049030be3ec4a3ba1a1' 
  AND token = 'BGbTckkZlAsxxw6l3ysBrX59Qgu0/gs5fqtFOdbzWDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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