SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5ab86bce08bc6084890d0945b74a3086827911a4c7544579f17d8a4fabbba15' 
  AND token = 'EEjAIAg2eo5n8QWdtC+LYNr/afOC5tgUkGz0rnZvHoc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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