SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6fbd9db40132fcdcab1574e839220a33e7f7084ea38526437d5d84135e561a9' 
  AND token = 'magf7ekrhriTfy1W3bIOSj9dZ+TYZqzroM8KJV4JBL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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