SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f838b6b4cfef75af17fbed0199a4d5c03832ec84284a7f339cbc340a8c5a9d40' 
  AND token = 'UA9jF4ThkzIui0uyrVDHnuyhM7KY49TB6MS64Js96zo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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