SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd912cf14d9ec1f3e20ff9ad877c822702dce5084031671c337abbfcb1875aeba' 
  AND token = 'Tn17SYSPy0KFw1lCdT0NcAiXLgNxehfZiy02fKZQZ4o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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