SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '481416b96ceb81714306c427ae9760cb9d5717e45009c86f95bd8e0c3b0bbc12' 
  AND token = 'jQGSOd0VKEj5pZuydmPVPKTSs0ZfwkaU5VEnQzb1Eng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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