SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8645fe690cd4a50a3ed8d73aaf5fac76e9861f85cba30b5be50040bbc74c47ec' 
  AND token = 'Lm/Ulc/7RwzPH3PE0RWq4baKm+B7PzcCPWH0qvlwI3I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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