SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb4b31c4c4fb45585b62896dffaea4c28e3dec9d728f9b2dbd79a35593bde00b' 
  AND token = 'vkbExz8rNrxUBFa6lDK2d1kA01yAiwcwLdWvAHj+wJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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