SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b74611ac7bd52b7ef6352ab99e01f0a015554221adf2ff7d05d16e6708b03a57' 
  AND token = 'OwLHjgxjaVEv6n3arwn3EsU1wN5owxt0h6gt6TpXw1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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