SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68b2a816999a4d1fc8c1bc45a1b03be2b350f7cee977b59fd039875f624673f4' 
  AND token = 'rDHT/QdjKNKSDT3gvxUIroyZXPRWaQOa+Fm/tJvcWMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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