SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f4f9a2acd8aa227a2d1928fab6a0dffddd15471c8e4f131422235c1b14372aa' 
  AND token = 'pr/3ghzF6hGBWV5tTVBvo7dZmroWGCrK7aGhggrTlCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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