SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '925f5ea4ea7f7f30688b11d961f5f3594c1e6e4b7b9cd3c46478733f445e2425' 
  AND token = 'S6NIWAGs+TmSvrIDBVVK8QaqAM8OHi0SHgHWq1kU/WM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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