SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d91c2d991830c2686bd2653bbafb462d842f58f21a7502f163306a068e5a31f' 
  AND token = 'Y2nEor5HbTp/KGvBVr+2olxrt5nVfmp72gjarzGHJ/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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