SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a11824bf9867610418f8193e08542267c52b725a8f78e3174c376f3436667cc8' 
  AND token = 'krKJ/xdnEpmYwPHBNI4auPcJBrZUVrJz+dbJc9OL7E0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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