SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3234a432cf6b99ce2323ae5bbe987132f804e295b851ccc4298d3ef5dafbba80' 
  AND token = 'CwucqeazPpZSaLoxOueWW4N1xruTuNzd8d5+4sexjIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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