SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c52b214958bcdde1a7cd23b5e18750e7b738934db811d3dd30b74fe48144a462' 
  AND token = 'OwkSudhpNRzfX+Bw0eRns3rr9aWcqSQQgucnaWTmT/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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