SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f3c985bd5a97b31a9a8e2ecc30b3dfb06cd841713b8483a1814d1954b5721ad' 
  AND token = 'juAQ2hjLSjtbrzWMF6PN2wnP2pOfh7btf2hO9j+8tug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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