SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eba85a1b1197057babcf48f025ee02cb25672df62d3ec96e6e359e364300de69' 
  AND token = 'poOnO7hUY/BG1OgcKzHv1ds5kpymUiJpz4NDwisgUIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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