SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8175db979483277055ec144f2b44191375c531fbf66b945d429ef5d45989b0d2' 
  AND token = 'AStXl70DAw/nAQ7mFyO+IoXgrkqacg+erMw292PmoFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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