SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f00ae51bf10124a4bb5d09b45fb77bd26adfae6da9b8c5ccfd8aa746ad0500d9' 
  AND token = 'ARppypWhOj5xMRsDzY92OAvuYMPNd8JaPz2UD2n3ddw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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