SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c27cf0721315568f3f300bd7ee99ea455df1b4446f62ba2781b53dd16f565ce5' 
  AND token = 'vDJqakBBgkspHYkgI5ynwaS0Kn17OH+FJKsyH8XhPJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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