SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b5a305614eed358477317f09719e3cde49932c72680bbbdd060abdad67356ed' 
  AND token = 'UC/aZ0oakOy6RooypsxHNBJs89ujBvmnZPfoVfufObo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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