SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '77bb9c6ec4284035e2e201a933539827e3edf8bb36536ddc9f63df193166c830' 
  AND token = '281+vUtP5MykYYMrZAzi0H4Wd49cProB7JmO+JJUGt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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