SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f10bf223958bf72a21760ddd1f6d0603046dddd83a9afbedf96109eab4848c' 
  AND token = 'ZV2Fk/QwtBrEFK29wNH1LJCmm6mRjK06VB5pDlKYxX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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