SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71ff62664ff8f2764741344bc004f40df3e9348db95ea0a9174bc7e110d1d399' 
  AND token = 'OVVUPUMiFrkBdvnqwj4gYamI/FfhsfICpXQfqmp4qvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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