SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b55e8ff9fcd9de7121c81c7e8d7317160f637ae6875d11889d56e8d96f72d4e9' 
  AND token = 'Ul9vb8YAFWVxSn7ccIGmahoPw1JxqjY1fQVN4Pkc2+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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