SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a8789ce8a39abce504342969f2e1a75f4252dda6a12656658db0f4a410de8ea5' 
  AND token = 'SlhOqciO3IVN81xj4NNT5lqiYLq0pGVUDl5guExKrVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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