SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50e5008f2a3dc29410396af8bef74922cd18084c168578092aff2445572dd574' 
  AND token = 'suDfH+63ZJ4/7PszEgLGzZpxr/d61GVTBUJY648Wovw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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