SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9fefa616087cc95252c0ea30c36c1628d142285b95f2ec7930ce9170635c666' 
  AND token = 'xNJHMZC9/JAtv00NUWWdbkjTJ1vyfZfzuvWuN+E/eLY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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