SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c42c19c8533853fc930ef1c0b2d407b684af05f1cc9e34d5fc0217e470648afa' 
  AND token = 'v/jWXAyB+7hgTBWQjpRqCUTjUqdWBDnN/LhIq1Rhdag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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