SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6267506de62d0bc1b3b4e90b55a4f1142afcd2d4921785189ae9d3f8d3be2e29' 
  AND token = 'gNss8Nqtt1pNi34Xgg+uwjVWWWEClruhXkXMDZy7GOM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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