SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a57289a2b65b5d9cbc0d4851820c61de3394952e5435f613b1af078acc0edfa' 
  AND token = '/MrJjATsBNGb1kZsxOQfgM+iGivgjoP9CKIkTE+9Ghw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}