SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ce8dd68137d91f040f8570decdf0f0de5a85057ae05500a10ef103a89b2be6' 
  AND token = 'XWnqOFDbBkAis18c/fQ5ESw/Ily95EIwf0XHMlCvO2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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