SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f853a07f44e029743fdf2e9d17e2e96a668d23dfc680c2bcec6bd3d6910abddc' 
  AND token = 's5teahLh64e5PTaADz+2R32UKbIfC4/xkrKVK00uIsc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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