SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8262e4aa6a99d3ecc47bee746345af1923cf813d6822d904a40a62eb30aa392c' 
  AND token = 'vAM8/bbg3xOz/7u1fw7eM9KRiUBMbHyOTwa2vsn+2BA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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