SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b5e55c1725bf6a1cc5327e50e8d61418116e0c6903159ae9805dedaf49a2578' 
  AND token = 'yQRYLmOr8FgovdGIqYxlAZ+AmCniZUsLEZzvujtuUrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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