SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a63881f6c2122a9be6f18e0cdee513136d6010f938ad53448bd500160266b3e' 
  AND token = 'wDeUX4vWmvRaykxlRMtI8KkwOhNLRKoSGtaTZ2hhr5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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