SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94a23e7a31f9bf52a698cb83f118afd8975725d7d305818f20602f175df13ceb' 
  AND token = '6v4nvzQpjitMRwblMAtNWWyDWVKQ2qP+dsIlYM0JcmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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