SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1486ccfb666b7852ce1be462313d69aac94add321200a43cab7ccd49fb01dc8' 
  AND token = 'JozBIwym+snqu8bv8qMLBPoH7fMNVQIJ2nTSkI2qXm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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