SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b3cf7075cc47861888cd9397b107280df04fed61957d88c39a836b37a21c389' 
  AND token = 'nHavVwfJEPaWacZL/+vhv9LoJafVwMNL1HfjIz3PUmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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