SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3fbc236cb3871135f8391369632306140546ebaf883af797c935fea48fb9e6b' 
  AND token = 'SmydSFRPESgEs5zfyuT/WWvK4tIHEkxHZgBfcKVh6gI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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