SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35589be0c26f8b2325eefe694a1194853281e7ecb6a27509662c80ec0635df2e' 
  AND token = 'UqMVejLqcisTmhjH3Xji/7nu4zYvI6FYOvRj/3Ma+ZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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