SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9db1cff545cd7a08986515c07862b479b97728972abd5f0d0cdf9285214e49b6' 
  AND token = 'KZl03slaRAGuZzlZvfeNAY2zDFWmKz56m3iEOhGo2Mk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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