SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77b2c5abeb111e0a0330a4731a442d823dbc388ebe70f1d55635cf995e10022f' 
  AND token = 'i+iG0coUXdFhEgqbJClm35q3B6wmHE5C497nj8PUqyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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