SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7a5e953823c3fd070f4c2aaf46bd0be18f2e98965833daba410f16a6d78e63d' 
  AND token = '63KtS9eBwg+Fn/kvW7nV0cNlnpbx45YOBx3lRDMX/AM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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