SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f844a2659f9ea297eee2a78bb9b9fdc6291aaa8964e7f3adfd45ffd9aaae74b3' 
  AND token = 'oeG89IGTJnxyC3lNRAw+e90YmFwATbQ9+fJRZSUMqPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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