SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31a873cbaf2ae31aaf74fdbc9954675e449fb3f4db3368f561940472102a1799' 
  AND token = 'ykQBdxqzU0cVISEqJTjoqWVc0C4WsSAIQ8zLwhZ84kg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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