SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '260518c396a7b9e922b21b93a484810d19243fe5e99cd98dcfb8c24e1614c8f1' 
  AND token = 'BaFzPoI4E4GgkN4DM2ZDkDqDL6zFH/zAtWPPEyMPqkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}