SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afde9e6a031913ff9340898af10482573ef359ebe8d3de7c006868527617cde9' 
  AND token = 'avlQzz9f4DB5dbWwcWa+RWrk+dqe7YqVIGLyqdiZ5JM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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