SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9afe56fe759ece77cfc248b9018ceeb853aa8de25301258068975ebf18d3cc9' 
  AND token = 'jfB9p2zg/SHiYvLlb0WZgGw7588EPvlOlHpMA4k/8z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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