SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2876f9cda52aa767d23ee11e6efe190a1bd91a5f4b1d045190a3186f969284ed' 
  AND token = 'YaJJ+JIUp10AVmKPV3/ZN5LkWezBYhnSVGaQf9f7MHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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