SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3fcaf97300bfd1845e709c8e2a3a296c35b6b95861d337cd16772fa446af603' 
  AND token = 'sIYzVlyTdf6BPtfs4DJOxuhtTDLleBPG3/fix1CCmH0=' 
  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"
    }
  }
}