SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '41936dab65cc5894ac6317df21cc37846041f412537cfd4faf04df9ed921b48c' 
  AND token = '7vhAlKLSJqqFuXJvRrmeSTMu+bSF3KymUM0hNT1Vwpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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