SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7fa172c86c29d0c73afb5702e8834d411033793506bb838653c4d66cb7b0495' 
  AND token = 'rQGBfHF/yuyBc6PgWmwhjQ/JYa7yvWLN8D+UmvRIeQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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