SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ed21aaee6d0f84950a3f045ad09ebbca475af78e1f4232f0fc277ee8e66912ac' 
  AND token = 'S8d10HZk3xunqzldVvpmcWxghmHbVYBBBWlE/xoToFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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