SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a924369cf488d16de800902002befacf95042a90fe624704e8f69b4d839d547' 
  AND token = '+TfSk8SoZLomdDHVO62RJ8UZmDpfbG9pT0v/WeGC96E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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