SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cf88841e820bca821dc635d4767a809f993fbf3ab4576abfc9778610978f443' 
  AND token = '/fvfVpXwjTrn6A/ZuYRmH+FMLOj4+wiig7LGS+/Zn7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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