SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f1fb1e648334bdefc0ecdf00d3344df72473d46f134a7c0fe7f2ed5590e6db9' 
  AND token = 'giSeO6JhYp3d+4PfmCdaKr+cpNbJ3rgH2naWtpggtX0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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