SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '63688e17b451506fce5a3e33f586175d31d24b7ccb7f2da8c0c6cc5aa32bf841' 
  AND token = '78kBIuSWT6kpiZR6EevQ+5nDgqdgtTDBI3J+T5JvWnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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